diff --git a/src/CommonElementsFinder.java b/src/CommonElementsFinder.java
index fb88a4b..2829e5d 100644
--- a/src/CommonElementsFinder.java
+++ b/src/CommonElementsFinder.java
@@ -1,3 +1,4 @@
+import java.util.HashSet;
 import java.util.Set;
 
 /**
@@ -15,7 +16,20 @@ public class CommonElementsFinder {
      */
     public static Set<Integer> findCommonElements(int[] array1, int[] array2) {
         // TODO
-        return null;
+        Set<Integer> elements = new HashSet<>();
+        Set<Integer> commonElements = new HashSet<>();
+
+        for (int num : array1) {
+            elements.add(num);
+        }
+
+        for (int num : array2) {
+            if (elements.contains(num)) {
+                commonElements.add(num);
+            }
+        }
+
+        return commonElements;
     }
 
 
diff --git a/src/DuplicateRemover.java b/src/DuplicateRemover.java
index 8d70003..54cac92 100644
--- a/src/DuplicateRemover.java
+++ b/src/DuplicateRemover.java
@@ -1,4 +1,7 @@
+import java.util.ArrayList;
 import java.util.List;
+import java.util.Set;
+import java.util.TreeSet;
 
 /**
  * The DuplicateRemover class provides a method to remove duplicate words
@@ -14,8 +17,16 @@ public class DuplicateRemover {
      * @return a sorted List<String> containing unique words from the input array
      */
     public static List<String> sortAndRemoveDuplicates(String[] words) {
-        // TODO
-        return null;
+        Set<String> unique = new TreeSet<>();
+        for (String word : words) {
+            unique.add(word);
+        }
+        List<String> wordList = new ArrayList<>();
+        for (String word : unique) {
+            wordList.add(word);
+        }
+
+        return wordList;
     }
 
     public static void main(String[] args) {
diff --git a/src/UniqueCharacterChecker.java b/src/UniqueCharacterChecker.java
index 554ffc4..d4a0f77 100644
--- a/src/UniqueCharacterChecker.java
+++ b/src/UniqueCharacterChecker.java
@@ -1,3 +1,6 @@
+import java.util.HashSet;
+import java.util.Set;
+
 /**
  * The UniqueCharacterChecker class provides a method to check if all characters
  * in a given word are unique.
@@ -14,7 +17,17 @@ public static boolean hasUniqueCharacters(String word) {
         // TODO: implement this!
         // Requirement: This must run in O(n) time, where n is the number of characters in the word
         // Hint: Stuck? Consider looking up "charAt" and seeing how it can help you
-        return false;
+        Set<Character> uniqueChar = new HashSet<>();
+
+        for (int i = 0; i < word.length(); i++) {
+            char currentChar = word.charAt(i);
+            if (uniqueChar.contains(currentChar)) {
+                return false;
+            }
+            uniqueChar.add(currentChar);
+        }
+
+        return true;
     }
 
     public static void main(String[] args) {