diff --git a/php/LICENSE b/php/LICENSE
new file mode 100755
index 00000000..08262f17
--- /dev/null
+++ b/php/LICENSE
@@ -0,0 +1,21 @@
+The MIT License
+
+Copyright (c) 2016 
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
\ No newline at end of file
diff --git a/php/README.md b/php/README.md
new file mode 100755
index 00000000..3a18a1d1
--- /dev/null
+++ b/php/README.md
@@ -0,0 +1,43 @@
+# Cracking the Code Interview with PHP
+> Cracking the code interview solutions for PHP developers
+
+Tested solutions for chapters.
+
+## Installation
+
+After you go into the app directory, you should execute following commands.
+OS X & Linux:
+
+```sh
+composer install
+```
+
+For installation, we need to consider these:
+
+ - Firstly, install PHP 7
+ - Secondly you can install PHPUnit globally for testing proposes
+ 
+Now, follow these steps:
+ - Clone repository
+ - composer install
+ 
+## Development setup
+
+To run all tests of the app, execute these commands in the app directory.
+
+```sh
+composer install
+phpunit
+```
+
+## Release History
+
+Refer to [CHANGELOG](https://github.com/midorikocak/ctci-php/CHANGELOG.md)
+
+## Meta
+
+Midori Kocak – [@midorikocak](https://twitter.com/midorikocak) – midori@mynameismidori.com
+
+Distributed under the MIT license. See ``LICENSE`` for more information.
+
+[https://github.com/midorikocak/ctci-php](https://github.com/midorikocak/ctci-php/)
\ No newline at end of file
diff --git a/php/composer.json b/php/composer.json
new file mode 100755
index 00000000..0e847def
--- /dev/null
+++ b/php/composer.json
@@ -0,0 +1,36 @@
+{
+    "name": "midorikocak/ctci-php",
+    "description": "php solutions of cracking the code interview using php",
+    "type": "project",
+    "license": "MIT",
+    "authors": [
+        {
+            "name": "Midori Kocak",
+            "email": "mtkocak@gmail.com"
+        }
+    ],
+    "minimum-stability": "dev",
+    "autoload": {
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+            "MidoriKocak\\": "src/",
+            "CTCILibrary\\":"src/CTCILibrary",
+            "Introduction\\":"src/Introduction",
+            "Chapter01\\Question1_1\\":"src/Chapter01/Question1_1",
+            "Chapter01\\Question1_2\\":"src/Chapter01/Question1_2",
+            "Chapter01\\Question1_3\\":"src/Chapter01/Question1_3",
+            "Chapter01\\Question1_4\\":"src/Chapter01/Question1_4",
+            "Chapter01\\Question1_5\\":"src/Chapter01/Question1_5",
+            "Chapter01\\Question1_6\\":"src/Chapter01/Question1_6",
+            "Chapter01\\Question1_7\\":"src/Chapter01/Question1_7",
+            "Chapter01\\Question1_8\\":"src/Chapter01/Question1_8",
+            "Chapter01\\Question1_9\\":"src/Chapter01/Question1_9",
+            "Chapter02\\Question2_5\\":"src/Chapter02/Question2_5"
+        },
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+    },
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+    }
+}
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new file mode 100644
index 00000000..e270922b
--- /dev/null
+++ b/php/composer.lock
@@ -0,0 +1,1428 @@
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+                "branch-alias": {
+                    "dev-master": "1.1-dev"
+                }
+            },
+            "autoload": {
+                "classmap": [
+                    "src/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Sebastian Bergmann",
+                    "email": "sebastian@phpunit.de"
+                }
+            ],
+            "description": "Allows reflection of object attributes, including inherited and non-public ones",
+            "homepage": "https://github.com/sebastianbergmann/object-reflector/",
+            "time": "2017-03-29 09:07:27"
+        },
+        {
+            "name": "sebastian/recursion-context",
+            "version": "dev-master",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/sebastianbergmann/recursion-context.git",
+                "reference": "a0e54bc9bf04e2c5b302236984cebc277631f0f1"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/sebastianbergmann/recursion-context/zipball/a0e54bc9bf04e2c5b302236984cebc277631f0f1",
+                "reference": "a0e54bc9bf04e2c5b302236984cebc277631f0f1",
+                "shasum": ""
+            },
+            "require": {
+                "php": "^7.0"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "^6.0"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "3.0.x-dev"
+                }
+            },
+            "autoload": {
+                "classmap": [
+                    "src/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Jeff Welch",
+                    "email": "whatthejeff@gmail.com"
+                },
+                {
+                    "name": "Sebastian Bergmann",
+                    "email": "sebastian@phpunit.de"
+                },
+                {
+                    "name": "Adam Harvey",
+                    "email": "aharvey@php.net"
+                }
+            ],
+            "description": "Provides functionality to recursively process PHP variables",
+            "homepage": "http://www.github.com/sebastianbergmann/recursion-context",
+            "time": "2017-03-07 15:09:59"
+        },
+        {
+            "name": "sebastian/resource-operations",
+            "version": "dev-master",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/sebastianbergmann/resource-operations.git",
+                "reference": "fadc83f7c41fb2924e542635fea47ae546816ece"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/sebastianbergmann/resource-operations/zipball/fadc83f7c41fb2924e542635fea47ae546816ece",
+                "reference": "fadc83f7c41fb2924e542635fea47ae546816ece",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.6.0"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.0.x-dev"
+                }
+            },
+            "autoload": {
+                "classmap": [
+                    "src/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Sebastian Bergmann",
+                    "email": "sebastian@phpunit.de"
+                }
+            ],
+            "description": "Provides a list of PHP built-in functions that operate on resources",
+            "homepage": "https://www.github.com/sebastianbergmann/resource-operations",
+            "time": "2016-10-03 07:43:09"
+        },
+        {
+            "name": "sebastian/version",
+            "version": "dev-master",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/sebastianbergmann/version.git",
+                "reference": "99732be0ddb3361e16ad77b68ba41efc8e979019"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/sebastianbergmann/version/zipball/99732be0ddb3361e16ad77b68ba41efc8e979019",
+                "reference": "99732be0ddb3361e16ad77b68ba41efc8e979019",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.6"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "2.0.x-dev"
+                }
+            },
+            "autoload": {
+                "classmap": [
+                    "src/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Sebastian Bergmann",
+                    "email": "sebastian@phpunit.de",
+                    "role": "lead"
+                }
+            ],
+            "description": "Library that helps with managing the version number of Git-hosted PHP projects",
+            "homepage": "https://github.com/sebastianbergmann/version",
+            "time": "2016-10-03 07:35:21"
+        },
+        {
+            "name": "webmozart/assert",
+            "version": "dev-master",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/webmozart/assert.git",
+                "reference": "4a8bf11547e139e77b651365113fc12850c43d9a"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/webmozart/assert/zipball/4a8bf11547e139e77b651365113fc12850c43d9a",
+                "reference": "4a8bf11547e139e77b651365113fc12850c43d9a",
+                "shasum": ""
+            },
+            "require": {
+                "php": "^5.3.3 || ^7.0"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "^4.6",
+                "sebastian/version": "^1.0.1"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.3-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Webmozart\\Assert\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Bernhard Schussek",
+                    "email": "bschussek@gmail.com"
+                }
+            ],
+            "description": "Assertions to validate method input/output with nice error messages.",
+            "keywords": [
+                "assert",
+                "check",
+                "validate"
+            ],
+            "time": "2016-11-23 20:04:41"
+        }
+    ],
+    "packages-dev": [],
+    "aliases": [],
+    "minimum-stability": "dev",
+    "stability-flags": {
+        "phpunit/phpunit": 20
+    },
+    "prefer-stable": false,
+    "prefer-lowest": false,
+    "platform": [],
+    "platform-dev": []
+}
diff --git a/php/phpunit.xml b/php/phpunit.xml
new file mode 100755
index 00000000..96a83abe
--- /dev/null
+++ b/php/phpunit.xml
@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<!-- http://www.phpunit.de/manual/current/en/appendixes.configuration.html -->
+<phpunit backupGlobals="false"
+         backupStaticAttributes="false"
+         bootstrap="vendor/autoload.php"
+         colors="true"
+         convertErrorsToExceptions="true"
+         convertNoticesToExceptions="true"
+         convertWarningsToExceptions="true"
+         processIsolation="false"
+         stopOnFailure="false"
+         syntaxCheck="false">
+
+    <testsuites>
+        <testsuite name="CTCI Test">
+            <directory suffix=".php">tests/</directory>
+        </testsuite>
+    </testsuites>
+
+    <php>
+        <server name="KERNEL_DIR" value="app/" />
+        <ini name="memory_limit" value="2048M" />
+        <ini name="xdebug.max_nesting_level" value="500" />
+    </php>
+</phpunit>
\ No newline at end of file
diff --git a/php/src/Chapter01/Question1_1/Question.php b/php/src/Chapter01/Question1_1/Question.php
new file mode 100644
index 00000000..1d36cf53
--- /dev/null
+++ b/php/src/Chapter01/Question1_1/Question.php
@@ -0,0 +1,33 @@
+<?php
+
+namespace Chapter01\Question1_1;
+
+
+class Question
+{
+    public static function isUniqueChars(string $string): bool
+    {
+        $chars = [];
+        for ($i = 0; $i < strlen($string); $i++) {
+            if (!isset($chars[$string[$i]])) {
+                $chars[$string[$i]] = true;
+            } else {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    public static function isUniqueChars2(string $string): bool
+    {
+        $checker = 0;
+        for ($i = 0; $i < strlen($string); $i++) {
+            $value = ord($string[$i]) - ord('a');
+            if (($checker & (1 << $value)) > 0) {
+                return false;
+            }
+            $checker |= (1 << $value);
+        }
+        return true;
+    }
+}
\ No newline at end of file
diff --git a/php/src/Chapter01/Question1_2/Question.php b/php/src/Chapter01/Question1_2/Question.php
new file mode 100644
index 00000000..3855d734
--- /dev/null
+++ b/php/src/Chapter01/Question1_2/Question.php
@@ -0,0 +1,75 @@
+<?php
+
+namespace Chapter01\Question1_2;
+
+
+class Question
+{
+
+    /**
+     * Sort strings,compare them.
+     *
+     * @param string $string1
+     * @param string $string2
+     * @return bool
+     */
+    public static function isPermutation(string $string1, string $string2): bool
+    {
+        $charArray1 = str_split($string1);
+        $charArray2 = str_split($string2);
+
+        sort($charArray1);
+        sort($charArray2);
+
+        if (sizeof($charArray1) != sizeof($charArray2)) {
+            return false;
+        }
+
+        $sortedString1 = implode('', $charArray1);
+        $sortedString2 = implode('', $charArray2);
+
+        if ($sortedString1 == $sortedString2) {
+            return true;
+        }
+
+        return false;
+    }
+
+
+    /**
+     * Check if two strings has identical character counts
+     *
+     * @param string $string1
+     * @param string $string2
+     * @return bool
+     */
+    public static function isPermutation2(string $string1, string $string2): bool
+    {
+        $letters = [];
+
+        if (strlen($string1) != strlen($string2)) {
+            return false;
+        }
+
+        for ($i = 0; $i < strlen($string1); $i++) {
+            if (!isset($letters[$string1[$i]])) {
+                $letters[$string1[$i]] = 1;
+            } else {
+                $letters[$string1[$i]]++;
+            }
+        }
+
+        for ($j = 0; $j < strlen($string2); $j++) {
+            if (!isset($letters[$string2[$j]])) {
+                return false;
+            } else {
+                $letters[$string2[$j]]--;
+                if ($letters[$string2[$j]] < 0) {
+                    return false;
+                }
+            }
+        }
+
+        return true;
+    }
+}
\ No newline at end of file
diff --git a/php/src/Chapter01/Question1_3/Question.php b/php/src/Chapter01/Question1_3/Question.php
new file mode 100644
index 00000000..aa5c7acf
--- /dev/null
+++ b/php/src/Chapter01/Question1_3/Question.php
@@ -0,0 +1,19 @@
+<?php
+
+namespace Chapter01\Question1_3;
+
+class Question
+{
+    public static function replaceSpaces(string $string): string
+    {
+        $result = "";
+        for ($i = 0; $i < strlen($string); $i++) {
+            if ($string[$i] == " ") {
+                $result .= "%20";
+            } else {
+                $result .= $string[$i];
+            }
+        }
+        return $result;
+    }
+}
\ No newline at end of file
diff --git a/php/src/Chapter01/Question1_4/Question.php b/php/src/Chapter01/Question1_4/Question.php
new file mode 100644
index 00000000..73fb51e8
--- /dev/null
+++ b/php/src/Chapter01/Question1_4/Question.php
@@ -0,0 +1,134 @@
+<?php
+
+namespace Chapter01\Question1_4;
+
+class Question
+{
+    public static function isPermutationOfPalindrome(string $string): bool
+    {
+        $charMap = self::buildCharFrequencyTable($string);
+        return self::checkMaxOneOdd($charMap);
+    }
+
+    public static function checkMaxOneOdd(array $charMap): bool
+    {
+        $foundOdd = false;
+        foreach ($charMap as $count) {
+            if ($count % 2 == 1) {
+                if ($foundOdd == true) {
+                    return false;
+                }
+                $foundOdd = true;
+            }
+        }
+        return true;
+    }
+
+    public static function buildCharFrequencyTable($string): array
+    {
+
+        $string = strtolower($string);
+        $string = str_replace(' ', '', $string);
+
+        $charMap = [];
+        for ($i = 0; $i < strlen($string); $i++) {
+            if (!isset($charMap[$string[$i]])) {
+                $charMap[$string[$i]] = 1;
+            } else {
+                $charMap[$string[$i]]++;
+            }
+        }
+        return $charMap;
+    }
+
+    public static function isPermutationOfPalindrome2(string $string): bool
+    {
+        $countOdd = 0;
+        $charMap = [];
+        for ($i = 0; $i < strlen($string); $i++) {
+            $charNumber = self::getCharNumber($string[$i]);
+
+            if ($charNumber != -1) {
+
+                if (!isset($charMap[$charNumber])) {
+                    $charMap[$charNumber] = 1;
+                } else {
+                    $charMap[$charNumber]++;
+                }
+
+                if ($charMap[$charNumber] % 2 == 1) {
+                    $countOdd++;
+                } else {
+                    $countOdd--;
+                }
+            }
+        }
+        return $countOdd <= 1;
+    }
+
+    public static function getCharNumber(string $char)
+    {
+        $char = strtolower($char);
+
+        if (strlen($char) != 1) {
+            // throw new \InvalidArgumentException('Char chould be one letter.');
+            return -1;
+        }
+        $ord = ord($char);
+        if (($ord >= ord('a') && $ord <= ord('z')) ||
+            ($ord >= ord('A') && $ord <= ord('Z'))
+        ) {
+            return $ord - ord('a');
+        } else {
+            return -1;
+        }
+    }
+
+    public static function isPermutationOfPalindrome3(string $string): bool
+    {
+        $bitVector = self::createBitVector($string);
+        // one odd letter or no odd letter
+        return $bitVector == 0 || self::checkExactlyOneBitSet($bitVector);
+    }
+
+    public static function createBitVector(string $string): int
+    {
+        $bitVector = 0;
+        for ($i = 0; $i < strlen($string); $i++) {
+            $index = self::getCharNumber($string[$i]);
+            $bitVector = self::toggle($bitVector, $index);
+        }
+        return $bitVector;
+    }
+
+    /**
+     * Flips bit at index
+     *
+     * @param int $bitVector
+     * @param int $index
+     * @return int
+     */
+    public static function toggle(int $bitVector, int $index): int
+    {
+        if ($index < 0) {
+            return $bitVector;
+        }
+
+        $mask = (1 << $index);
+
+        if (($bitVector & $mask) == 0) {
+            $bitVector |= $mask;
+        } else {
+            // ~00001000 = 11110111
+            $bitVector &= ~$mask;
+        }
+
+        return $bitVector;
+    }
+
+    public static function checkExactlyOneBitSet(int $bitVector)
+    {
+        // 00001000 & 00000111 = 00000000
+        return ($bitVector & ($bitVector - 1)) == 0;
+    }
+}
\ No newline at end of file
diff --git a/php/src/Chapter01/Question1_5/Question.php b/php/src/Chapter01/Question1_5/Question.php
new file mode 100644
index 00000000..0b1a849a
--- /dev/null
+++ b/php/src/Chapter01/Question1_5/Question.php
@@ -0,0 +1,82 @@
+<?php
+
+namespace Chapter01\Question1_5;
+
+class Question
+{
+    public static function oneEditAway(string $first, string $second): bool
+    {
+        if (strlen($first) == strlen($second)) {
+            return self::oneEditReplace($first, $second);
+        } elseif (strlen($first) + 1 == strlen($second)) {
+            return self::oneEditInsert($first, $second);
+        } elseif (strlen($first) - 1 == strlen($second)) {
+            return self::oneEditInsert($second, $first);
+        }
+
+        return false;
+    }
+
+    public static function oneEditReplace(string $first, string $second)
+    {
+        $foundDifference = false;
+        for ($i = 0; $i < strlen($first); $i++) {
+            if ($first[$i] != $second[$i]) {
+                if ($foundDifference) {
+                    return false;
+                }
+                $foundDifference = true;
+            }
+        }
+        return true;
+    }
+
+    public static function oneEditInsert(string $first, string $second)
+    {
+        $index1 = 0;
+        $index2 = 0;
+
+        while ($index1 < strlen($first) && $index2 < strlen($second)) {
+            if ($first[$index1] != $second[$index2]) {
+                if ($index1 != $index2) {
+                    return false;
+                }
+                $index2++;
+            } else {
+                $index1++;
+                $index2++;
+            }
+        }
+        return true;
+    }
+
+    public static function oneEditAway2(string $first, string $second): bool
+    {
+        if (abs(strlen($first) - strlen($second)) > 1) {
+            return false;
+        }
+        $shorter = strlen($first) >= strlen($second) ? $second : $first;
+        $longer = strlen($first) >= strlen($second) ? $first : $second;
+
+        $index1 = 0;
+        $index2 = 0;
+
+        $foundDifference = false;
+
+        while ($index2 < strlen($longer) && $index1 < strlen($shorter)) {
+            if ($longer[$index2] != $shorter[$index1]) {
+                if ($foundDifference) {
+                    return false;
+                }
+                $foundDifference = true;
+                if (strlen($shorter) == strlen($longer)) {
+                    $index1++; // on replace move shorter pointer
+                }
+            } else {
+                $index1++; // if matching move shorter pointer
+            }
+            $index2++; // Always move pointer for longer string;
+        }
+        return true;
+    }
+}
\ No newline at end of file
diff --git a/php/src/Chapter01/Question1_6/Question.php b/php/src/Chapter01/Question1_6/Question.php
new file mode 100644
index 00000000..f4fe082f
--- /dev/null
+++ b/php/src/Chapter01/Question1_6/Question.php
@@ -0,0 +1,48 @@
+<?php
+
+namespace Chapter01\Question1_6;
+
+class Question
+{
+    public static function countCompression(string $string): int
+    {
+        $compressedLength = 0;
+        $countConsecutive = 0;
+
+        for ($i = 0; $i < strlen($string); $i++) {
+            $countConsecutive++;
+
+            // if next char is the last char or next char is different
+            if ($i + 1 >= strlen($string) || $string[$i] != $string[$i + 1]) {
+                $count = strlen((string)$countConsecutive);
+                $compressedLength += 1 + $count;
+                $countConsecutive = 0;
+            }
+        }
+
+        return $compressedLength;
+    }
+
+    public static function compress(string $string): string
+    {
+        $finalLength = self::countCompression($string);
+        if ($finalLength >= strlen($string)) {
+            return $string;
+        }
+        $compressedString = "";
+        $countConsecutive = 0;
+
+        for ($i = 0; $i < strlen($string); $i++) {
+            $countConsecutive++;
+
+            // if next char is the last char or next char is different
+            if ($i + 1 >= strlen($string) || $string[$i] != $string[$i + 1]) {
+                $compressedString .= $string[$i];
+                $compressedString .= $countConsecutive;
+                $countConsecutive = 0;
+            }
+        }
+        
+        return $compressedString;
+    }
+}
\ No newline at end of file
diff --git a/php/src/Chapter01/Question1_7/Question.php b/php/src/Chapter01/Question1_7/Question.php
new file mode 100644
index 00000000..d3a6ccda
--- /dev/null
+++ b/php/src/Chapter01/Question1_7/Question.php
@@ -0,0 +1,39 @@
+<?php
+
+namespace Chapter01\Question1_7;
+
+class Question
+{
+    public static function rotate(array &$matrix)
+    {
+        if (sizeof($matrix) == 0 || sizeof($matrix) != sizeof($matrix[0])) {
+            return false;
+        }
+
+        $number = sizeof($matrix);
+
+
+        for ($layer = 0; $layer < $number / 2; $layer++) {
+            $first = $layer;
+            $last = $number - 1 - $layer;
+
+            for ($i = $first; $i < $last; $i++) {
+                $offset = $i - $first; // always starts from 0
+                $top = $matrix[$first][$i];
+
+                // left -> top
+                $matrix[$first][$i] = $matrix[$last - $offset][$first];
+
+                // bottom -> left
+                $matrix[$last - $offset][$first] = $matrix[$last][$last - $offset];
+
+                // right -> bottom
+                $matrix[$last][$last - $offset] = $matrix[$i][$last];
+
+                // top -> right
+                $matrix[$i][$last] = $top;
+            }
+        }
+        return $matrix;
+    }
+}
\ No newline at end of file
diff --git a/php/src/Chapter01/Question1_8/Question.php b/php/src/Chapter01/Question1_8/Question.php
new file mode 100644
index 00000000..dc4ce676
--- /dev/null
+++ b/php/src/Chapter01/Question1_8/Question.php
@@ -0,0 +1,47 @@
+<?php
+
+namespace Chapter01\Question1_8;
+
+class Question
+{
+    public static function setZeros(array $matrix)
+    {
+        $rows = [];
+        $columns = [];
+
+        for ($i = 0; $i < sizeof($matrix); $i++) {
+            for ($j = 0; $j < sizeof($matrix[0]); $j++) {
+                if ($matrix[$i][$j] == 0) {
+                    $rows[$i] = true;
+                    $columns[$j] = true;
+                }
+            }
+        }
+
+        foreach ($rows as $key => $value) {
+            self::nullifyRow($matrix, $key);
+        }
+
+        foreach ($columns as $key => $value) {
+            self::nullifyColumn($matrix, $key);
+        }
+
+        return $matrix;
+    }
+
+    public static function nullifyRow(array &$matrix, int $row)
+    {
+        for ($i = 0; $i < sizeof($matrix[0]); $i++) {
+            $matrix[$row][$i] = 0;
+        }
+    }
+
+    public static function nullifyColumn(array &$matrix, $column)
+    {
+        for ($i = 0; $i < sizeof($matrix); $i++) {
+            $matrix[$i][$column] = 0;
+        }
+    }
+
+
+}
\ No newline at end of file
diff --git a/php/src/Chapter01/Question1_9/Question.php b/php/src/Chapter01/Question1_9/Question.php
new file mode 100644
index 00000000..3be706dd
--- /dev/null
+++ b/php/src/Chapter01/Question1_9/Question.php
@@ -0,0 +1,22 @@
+<?php
+
+namespace Chapter01\Question1_9;
+
+class Question
+{
+    public static function isRotation(string $string1, string $string2): bool
+    {
+        $length = strlen($string1);
+        // Check that string1 and string2 are equal length and not empty
+        if ($length == strlen($string2) && $length > 0) {
+            $string3 = $string2 . $string2;
+            return self::isSubstring($string3, $string1);
+        }
+        return false;
+    }
+
+    public static function isSubstring(string $bigger, string $smaller): bool
+    {
+        return strpos($bigger, $smaller) !== false;
+    }
+}
\ No newline at end of file
diff --git a/php/src/Chapter02/Question2_5/QuestionA.php b/php/src/Chapter02/Question2_5/QuestionA.php
new file mode 100644
index 00000000..63c04fef
--- /dev/null
+++ b/php/src/Chapter02/Question2_5/QuestionA.php
@@ -0,0 +1,48 @@
+<?php
+
+namespace Chapter02\Question2_5;
+
+use CTCILibrary\LinkedListNode;
+
+class QuestionA
+{
+    public static function addLists(LinkedListNode $list1, LinkedListNode $list2)
+    {
+        $result = new LinkedListNode();
+        $current = $result;
+        $carry = 0;
+        $digit = 0;
+        $sum = 0;
+
+        while ($list1 || $list2) {
+
+            if ($list1 && $list2) {
+                $sum = $list1->data + $list2->data + $carry;
+                $digit = $sum % 10;
+                $carry = floor($sum / 10);
+            } elseif ($list1 && !$list2) {
+                $digit = $list1->data;
+            } elseif (!$list1 && $list2) {
+                $digit = $list2->data;
+            }
+
+            if ($current->data == null) {
+                $current->data = $digit;
+            } else {
+                $current->setNext(new LinkedListNode(intval($digit)));
+                $current = $current->next;
+            }
+
+
+            if ($list1) {
+                $list1 = $list1->next;
+            }
+
+            if ($list2) {
+                $list2 = $list2->next;
+            }
+        }
+
+        return $result;
+    }
+}
\ No newline at end of file
diff --git a/php/src/Chapter02/Question2_5/QuestionB.php b/php/src/Chapter02/Question2_5/QuestionB.php
new file mode 100644
index 00000000..3d27a10f
--- /dev/null
+++ b/php/src/Chapter02/Question2_5/QuestionB.php
@@ -0,0 +1,108 @@
+<?php
+
+namespace Chapter02\Question2_5;
+
+use CTCILibrary\LinkedListNode;
+
+class QuestionB
+{
+    public static function addLists(LinkedListNode $list1, LinkedListNode $list2)
+    {
+        $list1length = self::length($list1);
+        $list2length = self::length($list2);
+
+        $response = new LinkedListNode();
+
+        // Make their size equal
+        if ($list1length > $list2length) {
+            $amount = $list1length - $list2length;
+            $list2 = self::nodePad($list2, 0, $amount);
+        } elseif ($list2length > $list1length) {
+            $amount = $list2length - $list1length;
+            $list1 = self::nodePad($list1, 0, $amount);
+        }
+
+        $result = new LinkedListNode();
+        $current = $result;
+        $carry = 0;
+        $digit = 0;
+        $sum = 0;
+
+        while ($list1 || $list2) {
+
+            $sum = $list1->data + $list2->data;
+            $digit = $sum % 10;
+            $carry = floor($sum / 10);
+
+
+            // $current->data can be 0, with '==', 0 could be confused with null
+            if ($current->data === null) {
+                if ($carry == 1) {
+                    $result = new LinkedListNode($carry);
+                    $result->setNext($current);
+                }
+                $current->data = $digit;
+            } else {
+                if ($carry == 1) {
+                    $current->data += $carry;
+                }
+                $current->setNext(new LinkedListNode($digit));
+                $current = $current->next;
+            }
+
+            $list1 = $list1->next;
+            $list2 = $list2->next;
+        }
+
+        // Scan for cascading carry
+        $scan = $result;
+        while ($scan->next) {
+            if ($scan->next->data > 9) {
+                $carry = 1;
+                $scan->next->data %= 10;
+                $scan->data += $carry;
+
+                // start over
+                $scan = $result;
+                if ($scan->data > 9) {
+                    $result = new LinkedListNode(1);
+                    $scan->data %= 10;
+                    $result->setNext($scan);
+                }
+            }
+            $scan = $scan->next;
+        }
+
+        return $result;
+    }
+
+    public static function nodePad(LinkedListNode $list, int $value, $amount)
+    {
+        // Every time check the if null, if func has no typed params;
+        if ($amount == 0) {
+            return $list;
+        };
+
+        $newHead = new LinkedListNode($value);
+        $newTail = $newHead;
+
+        for ($i = 1; $i < $amount; $i++) {
+            $next = new LinkedListNode($value);
+            $newTail->setNext($next);
+            $newTail = $next;
+        }
+
+        $newTail->setNext($list);
+        return $newHead;
+    }
+
+    public static function length(LinkedListNode $list): int
+    {
+        $length = 0;
+        while ($list) {
+            $length++;
+            $list = $list->next;
+        }
+        return $length;
+    }
+}
\ No newline at end of file
diff --git a/php/src/CtCILibrary/AssortedMethods.php b/php/src/CtCILibrary/AssortedMethods.php
new file mode 100644
index 00000000..ec35f8f6
--- /dev/null
+++ b/php/src/CtCILibrary/AssortedMethods.php
@@ -0,0 +1,371 @@
+<?php
+
+namespace CTCILibrary;
+
+class AssortedMethods
+{
+    public static function randomInt(int $number): int
+    {
+        return (int)((float)rand() / (float)getrandmax()) * $number;
+    }
+
+    public static function randomIntInRange(int $min, int $max): int
+    {
+        // rand($max, $min); is already implemented in PHP
+        return self::randomInt($max + 1 - $min) + $min;
+    }
+
+    public static function randomBoolean($percentTrue = null): bool
+    {
+        if (isset($percentTrue)) {
+
+            return self::randomIntInRange(0, 100) < $percentTrue;
+        }
+        return self::randomIntInRange(0, 1) == 0;
+    }
+
+    public static function getListOfWords()
+    {
+        // Words in the dictionary.
+        $wordList = ["the", "of", "and", "a", "to", "in", "is", "be",
+            "that", "was", "world", "awesome", "he", "for", "it", "with",
+            "as", "his", "I", "on", "have", "at", "by", "not", "surely",
+            "they", "this", "attract", "computer", "had", "are", "but",
+            "from", "or", "she", "an", "which", "you", "one", "we", "all",
+            "were", "her", "would", "there", "their", "will", "when",
+            "who", "him", "been", "has", "more", "if", "no", "out", "do",
+            "so", "can", "what", "up", "said", "about", "other", "into",
+            "than", "its", "time", "only", "could", "new", "them", "man",
+            "some", "these", "then", "two", "first", "May", "any", "like",
+            "now", "my", "such", "make", "over", "our", "even", "most",
+            "me", "state", "after", "also", "made", "many", "did", "must",
+            "before", "back", "see", "through", "way", "where", "get",
+            "much", "go", "well", "your", "know", "should", "down", "work",
+            "year", "because", "come", "people", "just", "say", "each",
+            "those", "take", "day", "good", "how", "long", "Mr", "own",
+            "too", "little", "use", "us", "very", "great", "still", "men",
+            "here", "life", "both", "between", "old", "under", "last",
+            "never", "place", "same", "another", "think", "abuse", "house",
+            "while", "high", "right", "might", "came", "off", "find",
+            "states", "since", "used", "give", "against", "three",
+            "himself", "look", "few", "general", "heart", "hand", "school",
+            "resin", "part", "small", "American", "home", "during",
+            "number", "again", "Mrs", "around", "thought", "went",
+            "without", "however", "govern", "don't", "does", "got",
+            "public", "United", "point", "end", "become", "head", "once",
+            "course", "fact", "upon", "need", "system", "set", "every",
+            "trend", "war", "put", "form", "water", "took", "program",
+            "present", "government", "thing", "told", "possible", "group",
+            "large", "until", "always", "city", "didn't", "order", "away",
+            "called", "want", "eyes", "something", "unite", "going",
+            "face", "far", "asked", "interest", "later", "show", "knew",
+            "though", "less", "night", "early", "almost", "let", "open",
+            "enough", "side", "case", "days", "yet", "better", "nothing",
+            "tell", "problem", "toward", "given", "why", "national",
+            "room", "young", "social", "light", "business", "president",
+            "help", "power", "country", "next", "things", "word", "looked",
+            "real", "John", "line", "second", "church", "seem", "certain",
+            "big", "Four", "felt", "several", "children", "service",
+            "feel", "important", "rather", "name", "per", "among", "often",
+            "turn", "development", "keep", "family", "seemed", "white",
+            "company", "mind", "members", "others", "within", "done",
+            "along", "turned", "god", "sense", "week", "best", "change",
+            "kind", "began", "child", "ever", "law", "matter", "least",
+            "means", "question", "act", "close", "mean", "leave", "itself",
+            "force", "study", "York", "action", "it's", "door",
+            "experience", "human", "result", "times", "run", "different",
+            "car", "example", "hands", "whole", "center", "although",
+            "call", "Five", "inform", "gave", "plan", "woman", "boy",
+            "feet", "provide", "taken", "thus", "body", "play", "seen",
+            "today", "having", "cost", "perhaps", "field", "local",
+            "really", "am", "increase", "reason", "themselves", "clear",
+            "I'm", "information", "figure", "late", "above", "history",
+            "love", "girl", "held", "special", "move", "person", "whether",
+            "college", "sure", "probably", "either", "seems", "cannot",
+            "art", "free", "across", "death", "quite", "street", "value",
+            "anything", "making", "past", "brought", "moment", "control",
+            "office", "heard", "problems", "became", "full", "near",
+            "half", "nature", "hold", "live", "available", "known",
+            "board", "effect", "already", "Economic", "money", "position",
+            "believe", "age", "together", "shall", "TRUE", "political",
+            "court", "report", "level", "rate", "air", "pay", "community",
+            "complete", "music", "necessary", "society", "behind", "type",
+            "read", "idea", "wanted", "land", "party", "class", "organize",
+            "return", "department", "education", "following", "mother",
+            "sound", "ago", "nation", "voice", "six", "bring", "wife",
+            "common", "south", "strong", "town", "book", "students",
+            "hear", "hope", "able", "industry", "stand", "tax", "west",
+            "meet", "particular", "cut", "short", "stood", "university",
+            "spirit", "start", "total", "future", "front", "low",
+            "century", "Washington", "usually", "care", "recent",
+            "evidence", "further", "million", "simple", "road",
+            "sometimes", "support", "view", "fire", "says", "hard",
+            "morning", "table", "left", "situation", "try", "outside",
+            "lines", "surface", "ask", "modern", "top", "peace",
+            "personal", "member", "minutes", "lead", "schools", "talk",
+            "consider", "gone", "soon", "father", "ground", "living",
+            "months", "therefore", "America", "started", "longer", "Dr",
+            "dark", "various", "finally", "hour", "north", "third", "fall",
+            "greater", "pressure", "stage", "expected", "secretary",
+            "needed", "That's", "kept", "eye", "values", "union",
+            "private", "alone", "black", "required", "space", "subject",
+            "english", "month", "understand", "I'll", "nor", "answer",
+            "moved", "amount", "conditions", "direct", "red", "student",
+            "rest", "nations", "heart", "costs", "record", "picture",
+            "taking", "couldn't", "hours", "deal", "forces", "everything",
+            "write", "coming", "effort", "market", "island", "wall",
+            "purpose", "basis", "east", "lost", "St", "except", "letter",
+            "looking", "property", "Miles", "difference", "entire", "else",
+            "color", "followed", "feeling", "son", "makes", "friend",
+            "basic", "cold", "including", "single", "attention", "note",
+            "cause", "hundred", "step", "paper", "developed", "tried",
+            "simply", "can't", "story", "committee", "inside", "reached",
+            "easy", "appear", "include", "accord", "Actually", "remember",
+            "beyond", "dead", "shown", "fine", "religious", "continue",
+            "ten", "defense", "getting", "Central", "beginning", "instead",
+            "river", "received", "doing", "employ", "trade", "terms",
+            "trying", "friends", "sort", "administration", "higher",
+            "cent", "expect", "food", "building", "religion", "meeting",
+            "ready", "walked", "follow", "earth", "speak", "passed",
+            "foreign", "NATURAL", "medical", "training", "County", "list",
+            "floor", "piece", "especially", "indeed", "stop", "wasn't",
+            "England", "difficult", "likely", "Suddenly", "moral", "plant",
+            "bad", "club", "needs", "international", "working",
+            "countries", "develop", "drive", "reach", "police", "sat",
+            "charge", "farm", "fear", "test", "determine", "hair",
+            "results", "stock", "trouble", "happened", "growth", "square",
+            "William", "cases", "effective", "serve", "miss", "involved",
+            "doctor", "earlier", "increased", "being", "blue", "hall",
+            "particularly", "boys", "paid", "sent", "production",
+            "district", "using", "thinking", "concern", "Christian",
+            "press", "girls", "wide", "usual", "direction", "feed",
+            "trial", "walk", "begin", "weeks", "points", "respect",
+            "certainly", "ideas", "industrial", "methods", "operation",
+            "addition", "association", "combine", "knowledge", "decided",
+            "temperature", "statement", "Yes", "below", "game", "nearly",
+            "science", "directly", "horse", "influence", "size", "showed",
+            "build", "throughout", "questions", "character", "foot",
+            "Kennedy", "firm", "reading", "husband", "doubt", "services",
+            "according", "lay", "stay", "programs", "anyone", "average",
+            "French", "spring", "former", "summer", "bill", "lot",
+            "chance", "due", "comes", "army", "actual", "Southern",
+            "neither", "relate", "rise", "evening", "normal", "wish",
+            "visit", "population", "remain", "measure", "merely",
+            "arrange", "condition", "decision", "account", "opportunity",
+            "pass", "demand", "strength", "window", "active", "deep",
+            "degree", "ran", "western", "E", "sales", "continued", "fight",
+            "heavy", "arm", "standard", "generally", "carry", "hot",
+            "provided", "serious", "led", "wait", "hotel", "opened",
+            "performance", "maybe", "station", "changes", "literature",
+            "marry", "claim", "works", "bed", "wrong", "main", "unit",
+            "George", "hit", "planning", "supply", "systems", "add",
+            "chief", "officer", "Soviet", "pattern", "stopped", "price",
+            "success", "lack", "myself", "truth", "freedom", "manner",
+            "quality", "gun", "manufacture", "clearly", "share",
+            "movement", "length", "ways", "burn", "forms", "Organization",
+            "break", "somewhat", "efforts", "cover", "meaning", "progress",
+            "treatment", "beautiful", "placed", "happy", "attack",
+            "apparently", "blood", "groups", "carried", "sign", "radio",
+            "dance", "I've", "regard", "man's", "train", "herself",
+            "numbers", "corner", "REACTION", "immediately", "language",
+            "running", "recently", "shake", "larger", "lower", "machine",
+            "attempt", "learn", "couple", "race", "audience", "Oh",
+            "middle", "brown", "date", "health", "persons",
+            "understanding", "arms", "daily", "suppose", "additional",
+            "hospital", "pool", "technical", "served", "declare",
+            "described", "current", "poor", "steps", "reported", "sun",
+            "based", "produce", "determined", "receive", "park", "staff",
+            "faith", "responsibility", "Europe", "latter", "British",
+            "season", "equal", "learned", "practice", "green", "writing",
+            "ones", "choice", "fiscal", "term", "watch", "scene",
+            "activity", "product", "types", "ball", "heat", "clothe",
+            "lived", "distance", "parent", "letters", "returned",
+            "forward", "obtained", "offer", "specific", "straight", "fix",
+            "division", "slowly", "shot", "poet", "seven", "moving",
+            "mass", "plane", "proper", "propose", "drink", "obviously",
+            "plans", "whatever", "afternoon", "figures", "parts",
+            "approve", "saying", "born", "immediate", "fame", "gives",
+            "extent", "justice", "cars", "mark", "pretty", "opinion",
+            "ahead", "glass", "refuse", "enter", "completely", "send",
+            "desire", "judge", "none", "waiting", "popular", "Democratic",
+            "film", "mouth", "Corps", "importance", "touch", "director",
+            "ship", "there's", "council", "EFFECTS", "event", "worth",
+            "existence", "designed", "hardly", "indicated", "analysis",
+            "established", "products", "growing", "patient", "rule",
+            "bridge", "pain", "base", "check", "cities", "elements",
+            "leaders", "discussion", "limited", "sit", "Thomas",
+            "agreement", "gas", "factors", "marriage", "easily", "closed",
+            "excite", "accept", "applied", "allow", "bit", "married",
+            "oil", "Rhode", "shape", "interested", "strange", "compose",
+            "professional", "remained", "news", "Despite", "beauty",
+            "responsible", "wonder", "spent", "tear", "unless", "eight",
+            "permit", "covered", "Negro", "played", "I'd", "vote",
+            "balance", "Charles", "loss", "Commission", "original", "fair",
+            "reasons", "studies", "exactly", "built", "behavior", "enemy",
+            "teeth", "bank", "die", "James", "relations", "weight",
+            "prepared", "related", "sea", "bar", "warn", "post", "trees",
+            "official", "separate", "clay", "Sunday", "raised", "events",
+            "thin", "dropped", "cattle", "invite", "playing", "prevent",
+            "detail", "standing", "grow", "places", "someone", "bright",
+            "Talking", "meant", "print", "capital", "happen", "sides",
+            "everyone", "facilities", "filled", "lip", "essential",
+            "techniques", "June", "knows", "stain", "hadn't", "dinner",
+            "dog", "dollars", "caught", "shout", "buy", "divide",
+            "entered", "Chicago", "speed", "jazz", "appoint", "governor",
+            "institutions", "fit", "materials", "sight", "store",
+            "dependence", "explain", "gain", "he'd", "leadership", "quiet",
+            "realize", "parents", "Communist", "neighbor", "round",
+            "included", "kitchen", "thousand", "Christ", "isn't",
+            "radiation", "broad", "stops", "failure", "retire", "election",
+            "primary", "king", "books", "command", "edge", "ember",
+            "March", "sitting", "conference", "bottom", "lady", "advise",
+            "churches", "model", "battle", "giving", "sport", "address",
+            "considerable", "spread", "funds", "trip", "youth",
+            "CONSTRUCTION", "rock", "regular", "changed", "boat", "memory",
+            "successful", "captain", "hell", "brother", "murder", "quick",
+            "moreover", "highly", "difficulty", "inch", "saw", "clean",
+            "collect", "camp", "experiment", "shows", "Authority", "older",
+            "lord", "variety", "material", "frame", "distinguish",
+            "scientific", "introduce", "principal", "Jack", "kill",
+            "collection", "fell", "entertain", "pieces", "management",
+            "otherwise", "security", "danger", "entirely", "civil",
+            "frequently", "advertise", "records", "secret", "title",
+            "impossible", "yesterday", "fast", "Mike", "produced", "favor",
+            "noted", "caused", "lose", "purposes", "solid", "song",
+            "corporation", "lie", "winter", "dress", "electric", "key",
+            "dry", "reduce", "fresh", "goes", "hill", "names", "slow",
+            "quickly", "telephone", "threaten", "oppose", "deliver",
+            "officers", "expression", "published", "famous", "pray",
+            "adopt", "London", "clothes", "laws", "citizens", "announced",
+            "minute", "master", "sharp", "advantage", "greatest",
+            "relation", "Mary", "leaving", "gray", "manager", "animal",
+            "object", "bottle", "draw", "honor", "recognize", "drop",
+            "intend", "relationship", "opposite", "sources", "poetry",
+            "ability", "assistance", "operating", "bear", "join", "climb",
+            "companies", "exist", "fixed", "gradual", "possibility",
+            "hunt", "spoke", "satisfy", "units", "neck", "sleep",
+            "doesn't", "finished", "carefully", "facts", "nice",
+            "practical", "save", "takes", "allowed", "wine", "remind",
+            "rich", "financial", "dream", "knife", "stations", "civilize",
+            "Rose", "cool", "died", "thick", "imagine", "literary", "bind",
+            "inches", "earn", "familiar", "seeing", "distribution",
+            "marked", "coffee", "rules", "slip", "apply", "page", "beside",
+            "daughter", "Relatively", "classes", "explore", "stated",
+            "German", "musical", "smile", "significant", "block", "mix",
+            "reports", "PROPOSED", "shelter", "presence", "Affairs",
+            "named", "ordinary", "circumstances", "mile", "sweep",
+            "remains", "admire", "Catholic", "dust", "operations", "rain",
+            "tree", "nobody", "Henry", "Robert", "village", "advance",
+            "offered", "agree", "mechanic", "upper", "occasion",
+            "requirements", "capacity", "appears", "travel", "article",
+            "houses", "valley", "beat", "opening", "box", "evil",
+            "succeed", "surround", "application", "slightly", "remembered",
+            "interests", "warm", "subjects", "search", "presented", "shoe",
+            "sweet", "interesting", "membership", "suggest", "notice",
+            "connection", "extreme", "exchange", "flow", "spend",
+            "everybody", "poems", "campaign", "win", "forced", "freeze",
+            "nine", "eat", "newspaper", "please", "escape", "lives",
+            "swim", "file", "wind", "provides", "shop", "apartment",
+            "fashion", "reasonable", "created", "Germany", "watched",
+            "cells", "session", "somehow", "fully", "whose", "teacher",
+            "raise", "recognized", "unity", "Providence", "reference",
+            "explained", "twenty", "Russian", "features", "shoulder",
+            "sir", "forest", "studied", "Sam", "signal", "chair",
+            "reduced", "procedure", "forth", "limit", "disturb",
+            "universe", "mentioned", "pick", "reality", "differences",
+            "soft", "traditional", "Mission", "flat", "looks", "picked",
+            "weather", "smaller", "leg", "chairman", "ancient", "narrow",
+            "fellow", "twist", "belief", "excellent", "rights",
+            "vocational", "laid", "politics", "fill", "response",
+            "struggle", "disappear", "prove", "duty", "FOLLOWS", "editor",
+            "welcome", "anode", "possess", "hearing", "BUILDINGS", "ideal",
+            "scientist", "formed", "watching", "circle", "ought", "garden",
+            "library", "accuse", "message", "slight", "junior", "knock",
+            "empty", "protection", "treated", "birth", "expressed",
+            "planned", "choose", "confuse", "Virginia", "killed",
+            "frighten", "stayed", "worry", "surprise", "aside",
+            "photograph", "removed", "turning", "Jr", "pull", "personnel",
+            "agency", "pointed", "speech", "listen", "November", "sample",
+            "Louis", "motor", "selected", "Berlin", "CLAIMS", "spot",
+            "strike", "increasing", "exercise", "handle", "hole", "Leader",
+            "baby", "ride", "avoid", "cross", "twice", "commercial",
+            "failed", "prompt", "fat", "fourth", "visitor", "interior",
+            "Jewish", "wing", "desk", "faculty", "forget", "operate",
+            "stair", "besides", "relief", "standards", "France", "perfect",
+            "pour", "Nevertheless", "brief", "Jones", "kick", "attend",
+            "plus", "solution", "wage", "individuals", "powers",
+            "minister", "taste", "discovered", "pulled", "hire", "writer",
+            "verb", "preach", "friendly", "observed", "fan", "connect",
+            "Fig", "count", "egg", "items", "mention", "Texas",
+            "calculate", "platform", "drag", "mere", "tomorrow", "faces",
+            "pure", "fighting", "resources", "increases", "assumed",
+            "broke", "coast", "strict", "whom", "Russia", "qualify",
+            "Morgan", "victory", "fields", "pleasure", "contain", "fold",
+            "review", "April", "teach", "Richard", "whisper", "chosen",
+            "metal", "PRINCIPLES", "competition", "railroad", "safe",
+            "proved", "carrying", "horses", "kiss", "Mercer", "wheel",
+            "sail", "wants", "compared", "relieve", "approximately",
+            "wood", "historical", "persuade", "smiled", "crowd", "motion",
+            "shore", "suit", "calls", "seat", "deserve", "San", "snow",
+            "double", "educational", "neighborhood", "relative",
+            "teachers", "Independent", "puzzle", "nose", "dogs", "waited",
+            "naturally", "stone", "origin", "Rome", "wild", "scale",
+            "tremble", "drawn", "guess", "communism", "absence", "roof",
+            "sections", "sky", "walls", "Aircraft", "complain",
+            "independence", "busy", "elect", "revolution", "roar",
+            "willing", "League", "mine", "nurse", "liberal", "completed",
+            "poem", "dollar", "ordered", "levels", "ton", "settled",
+            "allowance", "bitter", "realized", "let's", "moon",
+            "sensitive", "servant", "hunger", "China", "sale",
+            "appearance", "lips", "policies", "actions", "strengthen",
+            "Monday", "onto", "directed", "leading", "machinery",
+            "theater", "Paris", "Frank", "somewhere", "Statements", "mill",
+            "projects", "starting", "hat", "ruin", "depend", "stands",
+            "signs", "families", "stir", "Khrushchev", "largely", "punish",
+            "drew", "breathe", "amuse", "characteristic", "electronic",
+            "pale", "pictures", "destroy", "expense", "somebody",
+            "completion", "disappoint", "fifty", "found", "soil", "flame",
+            "enjoy", "bless", "emotional", "promise", "she'd", "wave",
+            "commerce", "Jury", "bay", "tempt", "correct", "asking",
+            "content", "estimated", "conscious", "shine", "teaching",
+            "catch", "dish", "Saturday", "greet", "background", "flood",
+            "insect", "worse", "yellow", "occurred", "afraid", "ceremony",
+            "decrease", "trust", "yourself", "legs", "you've",
+            "communication", "describe", "sincere", "decide", "leaf",
+            "encourage", "rub", "declared", "cry", "bite", "July", "lung",
+            "significance", "helped", "gross", "apart", "disease",
+            "issues", "scratch", "dictionary", "risk", "broadcast", "drum",
+            "representative", "uncle", "cutting", "Jesus", "neglect",
+            "depth", "substantial", "GETS", "adventure", "beg", "entrance",
+            "plays", "throw", "ends", "Arts", "alive", "confidence",
+            "intellectual", "cheer", "properties", "experiments", "nut",
+            "plenty", "beneath", "closely", "description", "melt", "swear",
+            "tall", "loose", "area", "bury", "measured", "request",
+            "ourselves", "stream", "wipe", "band", "fingers", "creature",
+            "Hanover", "attorney", "load", "passing", "billion", "earnest",
+            "discussed", "translate", "achievement", "headquarters",
+            "inquiry", "rapidly", "express", "hesitate", "guard", "jobs",
+            "borrow", "owe", "Phil", "California", "ambition", "supposed",
+            "lake", "they're", "slope", "Typical", "spite", "wore", "dear",
+            "employees", "map", "pair", "spin", "one's", "praise",
+            "imagination", "hung", "instrument", "plow", "holding",
+            "objects", "straighten", "dominant", "scarce", "ring",
+            "matters", "creep", "plain", "resolution", "credit", "period",
+            "improve", "maintenance", "seize", "Laos", "we'll", "dozen",
+            "located", "dig", "towards", "curse", "major", "breath",
+            "weigh", "comfort", "federal", "guests", "priest", "sell",
+            "bodies", "female", "primarily", "cousin", "grew", "spiritual",
+            "dine", "engine", "politician", "custom", "educate",
+            "individual", "job", "Tom", "cook", "grass", "mail",
+            "salesman", "nail", "tap", "wet", "bedroom", "sufficient",
+            "chest", "dramatic", "silence", "behave", "breakfast",
+            "sudden", "passage", "scatter", "objection", "unusual",
+            "argument", "policy", "powerful", "throat", "formal", "rapid",
+            "Parker", "wrap", "luck", "grind", "rifle", "HIGHEST", "loan",
+            "represent", "skill", "spell", "broken", "arch", "angle",
+            "sick", "swell", "blind", "Contemporary", "engineer",
+            "military", "boundary", "location", "homes", "boil",
+            "officials", "operator", "Senate", "lend"];
+        return $wordList;
+    }
+}
\ No newline at end of file
diff --git a/php/src/CtCILibrary/LinkedListNode.php b/php/src/CtCILibrary/LinkedListNode.php
new file mode 100644
index 00000000..5532f073
--- /dev/null
+++ b/php/src/CtCILibrary/LinkedListNode.php
@@ -0,0 +1,76 @@
+<?php
+
+namespace CTCILibrary;
+
+use phpDocumentor\Reflection\DocBlock\Tags\Link;
+
+class LinkedListNode
+{
+    /**
+     * @var LinkedListNode
+     */
+    public $next;
+
+    /**
+     * Doubly Linked List
+     *
+     * @var LinkedListNode
+     */
+    public $prev;
+    public $last;
+    public $data;
+
+    public function __construct(int $data = null, LinkedListNode $next = null, LinkedListNode $prev = null)
+    {
+        if ($data !== null) {
+            $this->data = $data;
+        }
+        if ($next != null) {
+            $this->setNext($next);
+        }
+        if ($prev != null) {
+            $this->setPrev($prev);
+        }
+    }
+
+    public function setNext(LinkedListNode $next)
+    {
+        $this->next = $next;
+        if ($this == $this->last) {
+            $this->last = $next;
+        }
+        if ($next != null && $next->prev != $this) {
+            $next->setPrev($this);
+        }
+    }
+
+    public function setPrev(LinkedListNode $prev)
+    {
+        $this->prev = $prev;
+        if ($prev != null && $prev->next != $this) {
+            $prev->setNext($this);
+        }
+    }
+
+    public function printForward(): string
+    {
+        if ($this->next != null) {
+            return $this->data . "->" . $this->next->printForward();
+        } else {
+            // I don't know why she did this
+            return strval((int)$this->data);
+        }
+    }
+
+    public function cloneNode(): LinkedListNode
+    {
+        $next2 = null;
+        if ($this->next != null) {
+            // Makes a recursive call
+            $next2 = $this->next->cloneNode();
+        }
+
+        $head2 = new LinkedListNode($this->data, $next2);
+        return $head2;
+    }
+}
\ No newline at end of file
diff --git a/php/src/Introduction/CompareBinaryToHex.php b/php/src/Introduction/CompareBinaryToHex.php
new file mode 100644
index 00000000..98dcfcf0
--- /dev/null
+++ b/php/src/Introduction/CompareBinaryToHex.php
@@ -0,0 +1,66 @@
+<?php
+
+namespace Introduction;
+
+class CompareBinaryToHex
+{
+    public static function digitToValue(string $digit)
+    {
+        $asciiValue = ord($digit);
+        if ($asciiValue >= ord("0") && $asciiValue <= ord("9")) {
+            return intval($digit);
+        } elseif ($asciiValue >= ord("A") && $asciiValue <= ord("F")) {
+            return 10 + (ord($digit) - ord("A"));
+        } elseif ($asciiValue >= ord("a") && $asciiValue <= ord("f")) {
+            return 10 + (ord($digit) - ord("a"));
+        }
+        return -1;
+    }
+
+    /*
+     * Converts the number to it's decimal value
+     * Starts from leftmost digit.
+     *
+     * @param string $number
+     * @param int $base
+     * @return int
+     */
+    public static function convertToBase(string $number, int $base)
+    {
+        if ($base < 2 || ($base > 10 && $base != 16)) {
+            return -1;
+        }
+        $value = 0;
+        for ($i = strlen($number) - 1; $i >= 0; $i--) {
+            $digit = self::digitToValue($number[$i]);
+
+            if ($digit < 0 || $digit >= $base) {
+                return -1;
+            }
+
+            $exp = strlen($number) - 1 - $i;
+            $value += $digit * pow($base, $exp);
+        }
+
+        return $value;
+    }
+
+    /**
+     * Compares string values of a binary and hex numbers.
+     *
+     * @param string $binary
+     * @param string $hex
+     * @return bool
+     */
+    public static function compareBinToHex(string $binary, string $hex)
+    {
+        $number1 = self::convertToBase($binary, 2);
+        $number2 = self::convertToBase($hex, 16);
+
+        if ($number1 < 0 || $number2 < 0) {
+            return false;
+        } else {
+            return $number1 == $number2;
+        }
+    }
+}
\ No newline at end of file
diff --git a/php/src/Introduction/SwapMinMax.php b/php/src/Introduction/SwapMinMax.php
new file mode 100644
index 00000000..fe0b45f5
--- /dev/null
+++ b/php/src/Introduction/SwapMinMax.php
@@ -0,0 +1,163 @@
+<?php
+
+namespace Introduction;
+
+class SwapMinMax
+{
+    /**
+     * If the array does not have numeric, unique, incremental keys,
+     * for loop above aren't going to work.
+     *
+     * @param $array int[]
+     * @return mixed
+     */
+    public static function getMinIndexWithPointers(array $array)
+    {
+        reset($array);
+        $minIndex = key($array);
+
+        while (current($array)) {
+            if (current($array) < $array[$minIndex]) {
+                $minIndex = key($array);
+            }
+            next($array);
+        }
+        return $minIndex;
+    }
+
+    /**
+     * If the array does not have numeric, unique, incremental keys,
+     * for loop above aren't going to work.
+     *
+     * @param $array int[]
+     * @return mixed
+     */
+    public static function getMaxIndexWithPointers(array $array)
+    {
+        reset($array);
+        $maxIndex = key($array);
+
+        while (current($array)) {
+            if (current($array) > $array[$maxIndex]) {
+                $maxIndex = key($array);
+            }
+            next($array);
+        }
+        return $maxIndex;
+    }
+
+    /**
+     * Find indexes in one pass, and swap them.
+     *
+     * @param $array int[]
+     */
+    public static function swapMinMaxWithPointers(array &$array)
+    {
+        reset($array);
+        $maxIndex = key($array);
+        $minIndex = key($array);
+
+        while (current($array)) {
+            if (current($array) > $array[$maxIndex]) {
+                $maxIndex = key($array);
+            }
+            if (current($array) < $array[$minIndex]) {
+                $minIndex = key($array);
+            }
+            next($array);
+        }
+
+        $temp = $array[$maxIndex];
+        $array[$maxIndex] = $array[$minIndex];
+        $array[$minIndex] = $temp;
+    }
+
+
+    /**
+     * Returns min integer key of the array
+     * Can return only integer keys
+     *
+     * @param $array int[]
+     * @return int
+     */
+    public static function getMinIndex(array $array): int
+    {
+        $minIndex = 0;
+        for ($i = 1; $i < sizeof($array); $i++) {
+            if ($array[$i] < $array[$minIndex]) {
+                $minIndex = $i;
+            }
+        }
+        return $minIndex;
+    }
+
+    /**
+     * Returns max integer key of the array
+     * Can return only integer keys
+     *
+     * @param $array int[]
+     * @return int
+     */
+    public static function getMaxIndex(array $array): int
+    {
+        $maxIndex = 0;
+        for ($i = 1; $i < sizeof($array); $i++) {
+            if ($array[$i] > $array[$maxIndex]) {
+                $maxIndex = $i;
+            }
+        }
+        return $maxIndex;
+    }
+
+    /**
+     * Swaps desired element with key.
+     *
+     * Note: The keys should not be integer only.
+     * Think about a solution with mixed keys. Hence arrays are
+     * hashMaps in PHP.
+     *
+     * @param $array int []
+     * @param int $first
+     * @param int $second
+     */
+    public static function swap(array &$array, int $first, int $second)
+    {
+        $temp = $array[$first];
+        $array[$first] = $array[$second];
+        $array[$second] = $temp;
+    }
+
+    /**
+     * @param $array int []
+     */
+    public static function swapMinMaxBetter(array &$array)
+    {
+        $minIndex = self::getMinIndex($array);
+        $maxIndex = self::getMaxIndex($array);
+        self::swap($array, $minIndex, $maxIndex);
+    }
+
+    /**
+     * @param $array int []
+     */
+    public static function swapMinMax(array &$array)
+    {
+        $minIndex = 0;
+        for ($i = 1; $i < sizeof($array); $i++) {
+            if ($array[$i] < $array[$minIndex]) {
+                $minIndex = $i;
+            }
+        }
+
+        $maxIndex = 0;
+        for ($i = 1; $i < sizeof($array); $i++) {
+            if ($array[$i] > $array[$maxIndex]) {
+                $maxIndex = $i;
+            }
+        }
+
+        $temp = $array[$minIndex];
+        $array[$minIndex] = $array[$maxIndex];
+        $array[$maxIndex] = $temp;
+    }
+}
\ No newline at end of file
diff --git a/php/tests/Chapter01/Question1_1Test.php b/php/tests/Chapter01/Question1_1Test.php
new file mode 100644
index 00000000..f61b1406
--- /dev/null
+++ b/php/tests/Chapter01/Question1_1Test.php
@@ -0,0 +1,33 @@
+<?php
+
+use Chapter01\Question1_1\Question;
+
+class Question1_1Test extends \PHPUnit_Framework_TestCase
+{
+    protected $words;
+
+    protected function setUp()
+    {
+        $this->words = [
+            'abcde' => true,
+            'hello' => false,
+            'apple' => false,
+            'kite' => true,
+            'padle' => true
+        ];
+    }
+
+    public function testIsUniqueChars()
+    {
+        foreach ($this->words as $word => $result) {
+            $this->assertEquals(Question::isUniqueChars($word), $result);
+        }
+    }
+
+    public function testIsUniqueChars2()
+    {
+        foreach ($this->words as $word => $result) {
+            $this->assertEquals(Question::isUniqueChars2($word), $result);
+        }
+    }
+}
\ No newline at end of file
diff --git a/php/tests/Chapter01/Question1_2Test.php b/php/tests/Chapter01/Question1_2Test.php
new file mode 100644
index 00000000..612d48a0
--- /dev/null
+++ b/php/tests/Chapter01/Question1_2Test.php
@@ -0,0 +1,31 @@
+<?php
+
+use Chapter01\Question1_2\Question;
+
+class Question1_2Test extends \PHPUnit_Framework_TestCase
+{
+    protected $words;
+
+    protected function setUp()
+    {
+        $this->words = [
+            ['apple', 'papel', true],
+            ['carrot', 'tarroc', true],
+            ['hello', 'llloh', false]
+        ];
+    }
+
+    public function testIsPermutation()
+    {
+        foreach ($this->words as $check) {
+            $this->assertEquals($check[2], Question::isPermutation($check[0], $check[1]));
+        }
+    }
+
+    public function testIsPermutation2()
+    {
+        foreach ($this->words as $check) {
+            $this->assertEquals($check[2], Question::isPermutation2($check[0], $check[1]));
+        }
+    }
+}
\ No newline at end of file
diff --git a/php/tests/Chapter01/Question1_3Test.php b/php/tests/Chapter01/Question1_3Test.php
new file mode 100644
index 00000000..8a9148a4
--- /dev/null
+++ b/php/tests/Chapter01/Question1_3Test.php
@@ -0,0 +1,18 @@
+<?php
+
+use Chapter01\Question1_3\Question;
+
+class Question1_3Test extends \PHPUnit_Framework_TestCase
+{
+    protected $word;
+
+    protected function setUp()
+    {
+        $this->word = ['abc d e f', 'abc%20d%20e%20f'];
+    }
+
+    public function testReplaceSpaces()
+    {
+        $this->assertEquals($this->word[1], Question::replaceSpaces($this->word[0]));
+    }
+}
\ No newline at end of file
diff --git a/php/tests/Chapter01/Question1_4Test.php b/php/tests/Chapter01/Question1_4Test.php
new file mode 100644
index 00000000..8f6a6986
--- /dev/null
+++ b/php/tests/Chapter01/Question1_4Test.php
@@ -0,0 +1,34 @@
+<?php
+
+use Chapter01\Question1_4\Question;
+
+class Question1_4Test extends \PHPUnit_Framework_TestCase
+{
+    protected $words;
+
+    protected function setUp()
+    {
+        $this->words = ['Tact Coa' => true, 'mustafa' => false];
+    }
+
+    public function testIsPermutationOfPalindrome()
+    {
+        foreach ($this->words as $word => $result) {
+            $this->assertEquals($result, Question::isPermutationOfPalindrome($word));
+        }
+    }
+
+    public function testIsPermutationOfPalindrome2()
+    {
+        foreach ($this->words as $word => $result) {
+            $this->assertEquals($result, Question::isPermutationOfPalindrome2($word));
+        }
+    }
+
+    public function testIsPermutationOfPalindrome3()
+    {
+        foreach ($this->words as $word => $result) {
+            $this->assertEquals($result, Question::isPermutationOfPalindrome3($word));
+        }
+    }
+}
\ No newline at end of file
diff --git a/php/tests/Chapter01/Question1_5Test.php b/php/tests/Chapter01/Question1_5Test.php
new file mode 100644
index 00000000..9245e235
--- /dev/null
+++ b/php/tests/Chapter01/Question1_5Test.php
@@ -0,0 +1,31 @@
+<?php
+
+use Chapter01\Question1_5\Question;
+
+class Question1_5Test extends \PHPUnit_Framework_TestCase
+{
+    protected $words;
+
+    protected function setUp()
+    {
+        $this->words = [
+            ['apple', 'appla', true],
+            ['apple', 'aple', true],
+            ['apple', 'app', false]
+        ];
+    }
+
+    public function testOneEditReplace()
+    {
+        foreach ($this->words as $check) {
+            $this->assertEquals($check[2], Question::oneEditAway($check[0], $check[1]));
+        }
+    }
+
+    public function testOneEditReplace2()
+    {
+        foreach ($this->words as $check) {
+            $this->assertEquals($check[2], Question::oneEditAway2($check[0], $check[1]));
+        }
+    }
+}
\ No newline at end of file
diff --git a/php/tests/Chapter01/Question1_6Test.php b/php/tests/Chapter01/Question1_6Test.php
new file mode 100644
index 00000000..f6de58a4
--- /dev/null
+++ b/php/tests/Chapter01/Question1_6Test.php
@@ -0,0 +1,22 @@
+<?php
+
+use Chapter01\Question1_6\Question;
+
+class Question1_6Test extends \PHPUnit_Framework_TestCase
+{
+    protected $words;
+
+    protected function setUp()
+    {
+        $this->words = [
+            'aabcccccaaa' => 'a2b1c5a3'
+        ];
+    }
+
+    public function testIsPermutation()
+    {
+        foreach ($this->words as $uncompressed => $compressed) {
+            $this->assertEquals($compressed, Question::compress($uncompressed));
+        }
+    }
+}
\ No newline at end of file
diff --git a/php/tests/Chapter01/Question1_7Test.php b/php/tests/Chapter01/Question1_7Test.php
new file mode 100644
index 00000000..79113859
--- /dev/null
+++ b/php/tests/Chapter01/Question1_7Test.php
@@ -0,0 +1,46 @@
+<?php
+
+use Chapter01\Question1_7\Question;
+
+class Question1_7Test extends \PHPUnit_Framework_TestCase
+{
+    protected $matrix1;
+    protected $matrix1rotated;
+    protected $matrix2;
+    protected $matrix2rotated;
+
+    protected function setUp()
+    {
+        $this->matrix1 = [
+            [1, 2, 3, 4],
+            [5, 6, 7, 8],
+            [9, 10, 11, 12],
+            [13, 14, 15, 16]
+        ];
+
+        $this->matrix1rotated = [
+            [13, 9, 5, 1],
+            [14, 10, 6, 2],
+            [15, 11, 7, 3],
+            [16, 12, 8, 4]
+        ];
+
+        $this->matrix2 = [
+            [1, 2, 3],
+            [5, 6, 7],
+            [9, 10, 11]
+        ];
+
+        $this->matrix2rotated = [
+            [9, 5, 1],
+            [10, 6, 2],
+            [11, 7, 3]
+        ];
+    }
+
+    public function testRotate()
+    {
+        $this->assertEquals($this->matrix1rotated, Question::rotate($this->matrix1));
+        $this->assertEquals($this->matrix2rotated, Question::rotate($this->matrix2));
+    }
+}
\ No newline at end of file
diff --git a/php/tests/Chapter01/Question1_8Test.php b/php/tests/Chapter01/Question1_8Test.php
new file mode 100644
index 00000000..2a4ad7db
--- /dev/null
+++ b/php/tests/Chapter01/Question1_8Test.php
@@ -0,0 +1,31 @@
+<?php
+
+use Chapter01\Question1_8\Question;
+
+class Question1_8Test extends \PHPUnit_Framework_TestCase
+{
+    protected $matrix;
+    protected $matrixZeros;
+
+    protected function setUp()
+    {
+        $this->matrix = [
+            [1, 2, 0, 4],
+            [5, 6, 7, 8],
+            [0, 10, 11, 12],
+            [13, 14, 15, 16]
+        ];
+
+        $this->matrixZeros = [
+            [0, 0, 0, 0],
+            [0, 6, 0, 8],
+            [0, 0, 0, 0],
+            [0, 14, 0, 16]
+        ];
+
+    }
+    public function testSetZeros()
+    {
+        $this->assertEquals($this->matrixZeros, Question::setZeros($this->matrix));
+    }
+}
\ No newline at end of file
diff --git a/php/tests/Chapter01/Question1_9Test.php b/php/tests/Chapter01/Question1_9Test.php
new file mode 100644
index 00000000..9b0e5d58
--- /dev/null
+++ b/php/tests/Chapter01/Question1_9Test.php
@@ -0,0 +1,25 @@
+<?php
+
+use Chapter01\Question1_9\Question;
+
+class Question1_9Test extends \PHPUnit_Framework_TestCase
+{
+    protected $words;
+
+    protected function setUp()
+    {
+        $this->words = [
+            ['apple', 'pleap', true],
+            ['waterbottle', 'erbottlewat', true],
+            ['camera', 'macera', false]
+        ];
+    }
+
+
+    public function testIsRotation()
+    {
+        foreach ($this->words as $check) {
+            $this->assertEquals($check[2], Question::isRotation($check[0], $check[1]));
+        }
+    }
+}
\ No newline at end of file
diff --git a/php/tests/Chapter02/Question2_5Test.php b/php/tests/Chapter02/Question2_5Test.php
new file mode 100644
index 00000000..6fb8e5b1
--- /dev/null
+++ b/php/tests/Chapter02/Question2_5Test.php
@@ -0,0 +1,58 @@
+<?php
+
+use Chapter02\Question2_5\QuestionA;
+use Chapter02\Question2_5\QuestionB;
+use CTCILibrary\LinkedListNode;
+
+class Question2_5Test extends \PHPUnit_Framework_TestCase
+{
+    public function testQuestionA()
+    {
+        $list1 = new LinkedListNode(7, new LinkedListNode(1, new LinkedListNode(6)));
+        $list2 = new LinkedListNode(5, new LinkedListNode(9, new LinkedListNode(2)));
+        $result = new LinkedListNode(2, new LinkedListNode(1, new LinkedListNode(9)));
+        $response = QuestionA::addLists($list1, $list2);
+
+        $this->assertEquals($result->printForward(), $response->printForward());
+    }
+
+    public function testQuestionB()
+    {
+        $list1 = new LinkedListNode(6, new LinkedListNode(1, new LinkedListNode(7)));
+        $list2 = new LinkedListNode(2, new LinkedListNode(9, new LinkedListNode(5)));
+        $result = new LinkedListNode(9, new LinkedListNode(1, new LinkedListNode(2)));
+        $response = QuestionB::addLists($list1, $list2);
+
+        $this->assertEquals($result->printForward(), $response->printForward());
+    }
+
+    public function testQuestionBCarryCascade()
+    {
+        $list1 = new LinkedListNode(5, new LinkedListNode(6, new LinkedListNode(9)));
+        $list2 = new LinkedListNode(7, new LinkedListNode(8, new LinkedListNode(4)));
+        $result = new LinkedListNode(1, new LinkedListNode(3, new LinkedListNode(5, new LinkedListNode(3))));
+        $response = QuestionB::addLists($list1, $list2);
+
+        $this->assertEquals($result->printForward(), $response->printForward());
+    }
+
+    public function testQuestionBCarryCascade2()
+    {
+        $list1 = new LinkedListNode(4, new LinkedListNode(4, new LinkedListNode(5)));
+        $list2 = new LinkedListNode(5, new LinkedListNode(5, new LinkedListNode(5)));
+        $result = new LinkedListNode(1, new LinkedListNode(0, new LinkedListNode(0, new LinkedListNode(0))));
+        $response = QuestionB::addLists($list1, $list2);
+
+        $this->assertEquals($result->printForward(), $response->printForward());
+    }
+
+    public function testQuestionBDiffSize()
+    {
+        $list1 = new LinkedListNode(6, new LinkedListNode(1, new LinkedListNode(7)));
+        $list2 = new LinkedListNode(2, new LinkedListNode(9));
+        $result = new LinkedListNode(6, new LinkedListNode(4, new LinkedListNode(6)));
+        $response = QuestionB::addLists($list1, $list2);
+
+        $this->assertEquals($result->printForward(), $response->printForward());
+    }
+}
\ No newline at end of file
diff --git a/php/tests/Introduction/CompareBinaryToHexTest.php b/php/tests/Introduction/CompareBinaryToHexTest.php
new file mode 100755
index 00000000..f3376b53
--- /dev/null
+++ b/php/tests/Introduction/CompareBinaryToHexTest.php
@@ -0,0 +1,24 @@
+<?php
+
+use Introduction\CompareBinaryToHex;
+
+class CompareBinaryToHexTest extends \PHPUnit_Framework_TestCase
+{
+    public function testDigitToValue()
+    {
+        $value = CompareBinaryToHex::digitToValue("C");
+        $this->assertEquals(12, $value);
+    }
+
+    public function testConvertToBase()
+    {
+        $converted = CompareBinaryToHex::convertToBase("100000", 2);
+        $this->assertEquals(32, $converted);
+    }
+
+    public function testCompareBinToHex()
+    {
+        $compared = CompareBinaryToHex::compareBinToHex("111001011", "1CB");
+        $this->assertTrue($compared);
+    }
+}
diff --git a/php/tests/Introduction/SwapMinMaxTest.php b/php/tests/Introduction/SwapMinMaxTest.php
new file mode 100755
index 00000000..4a74db06
--- /dev/null
+++ b/php/tests/Introduction/SwapMinMaxTest.php
@@ -0,0 +1,56 @@
+<?php
+
+use Introduction\SwapMinMax;
+
+class SwapMinMaxHexTest extends \PHPUnit_Framework_TestCase
+{
+    public $array = [10, -10, 10];
+
+    public function testGetMinIndexWithPointers()
+    {
+        $value = SwapMinMax::getMinIndexWithPointers($this->array);
+        $this->assertEquals(1, $value);
+    }
+
+    public function testGetMaxIndexWithPointers()
+    {
+        $value = SwapMinMax::getMaxIndexWithPointers($this->array);
+        $this->assertEquals(0, $value);
+    }
+
+    public function testSwapMinMaxWithPointers()
+    {
+        SwapMinMax::swapMinMaxWithPointers($this->array);
+        $this->assertEquals([-10, 10, 10], $this->array);
+    }
+
+    public function testGetMinIndex()
+    {
+        $value = SwapMinMax::getMinIndex($this->array);
+        $this->assertEquals(1, $value);
+    }
+
+    public function testGetMaxIndex()
+    {
+        $value = SwapMinMax::getMaxIndex($this->array);
+        $this->assertEquals(0, $value);
+    }
+
+    public function testSwap()
+    {
+        SwapMinMax::swap($this->array, 1, 2);
+        $this->assertEquals([10, 10, -10], $this->array);
+    }
+
+    public function testSwapMinMaxBetter()
+    {
+        SwapMinMax::swapMinMaxBetter($this->array);
+        $this->assertEquals([-10, 10, 10], $this->array);
+    }
+
+    public function testSwapMinMax()
+    {
+        SwapMinMax::swapMinMax($this->array);
+        $this->assertEquals([-10, 10, 10], $this->array);
+    }
+}