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Finished the assignment. #15

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362a7f2
Worked on some problems
kimageary Oct 22, 2024
5c4a3cd
Saving my work
kimageary Oct 24, 2024
0539d19
Finished the assignment
kimageary Oct 24, 2024
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61 changes: 41 additions & 20 deletions src/Main.java
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,7 @@
public class Main {

// The time complexity is:
// YOUR ANSWER HERE
// O(N)^2
public static void timesTable(int x) {
for(int i = 1; i <= x; i++) {
for(int j = 1; j <= x; j++) {
Expand All @@ -17,7 +17,7 @@ public static void timesTable(int x) {
}

// The time complexity is:
// YOUR ANSWER HERE
// O(N)
public static void printLetters(String word) {
char[] letters = word.toCharArray();

Expand All @@ -27,7 +27,7 @@ public static void printLetters(String word) {
}

// The time complexity is:
// YOUR ANSWER HERE
// O(N)
public static boolean isBanned(String password) {
String[] bannedPasswords = {"password", "hello", "qwerty"};
boolean banned = false;
Expand All @@ -41,7 +41,7 @@ public static boolean isBanned(String password) {


// The time complexity is:
// YOUR ANSWER HERE
// O(N) where N is the length of the array
public static int computeProduct(int[] nums) {
int total = 1;
for(int num : nums) {
Expand All @@ -51,7 +51,7 @@ public static int computeProduct(int[] nums) {
}

// The time complexity is:
// YOUR ANSWER HERE
// O(N)
public static void describeProduct(int[] nums) {
System.out.println("About to compute the product of the array...");
int product = computeProduct(nums);
Expand All @@ -60,7 +60,7 @@ public static void describeProduct(int[] nums) {


// The time complexity is:
// YOUR ANSWER HERE
// O(N)
public static int computeFactorial(int n) {
int result = 1;
for(int i = 1; i <= n; i++) {
Expand All @@ -71,6 +71,7 @@ public static int computeFactorial(int n) {

// Assume that the largest number is no bigger than the length
// of the array
// O(N) where N is the length of the array
public static void computeAllFactorials(int[] nums) {
for(int num : nums) {
int result = computeFactorial(num);
Expand All @@ -80,7 +81,7 @@ public static void computeAllFactorials(int[] nums) {


// The time complexity is:
// YOUR ANSWER HERE
// O(N) where n is equal to the lenght of arr
public static void checkIfContainedArrayList(ArrayList<String> arr, String target) {
if (arr.contains(target)) {
System.out.println(target + " is present in the list");
Expand All @@ -92,7 +93,7 @@ public static void checkIfContainedArrayList(ArrayList<String> arr, String targe

// assume n = wordsA.length = wordsB.length
// The time complexity is:
// YOUR ANSWER HERE
// O(N)^2
public static boolean containsOverlap(String[] wordsA, String[] wordsB) {
for(String wordA : wordsA) {
for(String wordB : wordsB) {
Expand All @@ -105,7 +106,7 @@ public static boolean containsOverlap(String[] wordsA, String[] wordsB) {
}

// The time complexity is:
// YOUR ANSWER HERE
// O(N)
public static boolean containsOverlap2(String[] wordsA, String[] wordsB) {
Set<String> wordsSet = new HashSet<>();
for(String word : wordsA) {
Expand All @@ -122,20 +123,20 @@ public static boolean containsOverlap2(String[] wordsA, String[] wordsB) {
}

// The time complexity is:
// YOUR ANSWER HERE
// O(N) where n is equal to the legnth of chars array
public static void printCharacters(char[] chars) {
for (int i = 0; i < chars.length; i++) {
char character = chars[i];
System.out.println("The character at index " + i + " is " + character);
}
}
// The time complexity is:
// YOUR ANSWER HERE
// O(1)
public static double computeAverage(double a, double b) {
return (a + b) / 2.0;
}
// The time complexity is:
// YOUR ANSWER HERE
// O(1)
public static void checkIfContainedHashSet(HashSet<String> set, String target)
{
if (set.contains(target)) {
Expand All @@ -150,7 +151,7 @@ public static void checkIfContainedHashSet(HashSet<String> set, String target)
// A queryName is given, and this method returns the corresponding email if it is found
// Otherwise, it returns "Person not found"
// What is the time complexity of this method?
// YOUR ANSWER HERE
// O(N) where n is equal to the length ot the names array
public static String emailLookup(String[] names, String[] emails, String queryName) {
for(int i = 0; i < names.length; i++) {
if (names[i].equals(queryName)) {
Expand All @@ -165,14 +166,19 @@ public static String emailLookup(String[] names, String[] emails, String queryNa
// keys are names and the values are emails.
// Write this method to efficiently return the corresponding email or "Person not found" if appropriate
// What is the time complexity of your solution?
// YOUR ANSWER HERE
// O(1)
public static String emailLookupEfficient(HashMap<String, String> namesToEmails, String queryName) {
return null;
if(namesToEmails.containsKey(queryName)){
return namesToEmails.get(queryName);
} else{
return "Person not found";
}
}

// What is the time complexity of this method?
// (assume the set and list have the same number of elements)
// YOUR ANSWER HERE
// O(N * M) where n is equal to the length of the wordSet hashset
// and m is equal to the length of the wordList
public static boolean hasCommon(HashSet<String> wordSet, ArrayList<String> wordList) {
for(String word : wordSet) {
if(wordList.contains(word)) {
Expand All @@ -186,28 +192,43 @@ public static boolean hasCommon(HashSet<String> wordSet, ArrayList<String> wordL
// What is the time complexity of your new solution?
// YOUR ANSWER HERE
public static boolean hasCommonEfficient(HashSet<String> wordSet, ArrayList<String> wordList) {
return false;
for (String word : wordList) {
if (wordSet.contains(word)) {
return true;
}
}
return false;
}

// Suppose you are building a dashboard that displays real-time stock prices.
// You want to keep track of the current price of each stock, with the stock's ticker symbol as the key.
// The prices will be updated frequently throughout the day, and you need to efficiently update
// and access the current price for each stock. The order of the ticker symbols is not important.
// What would be a good choice of data structure?
// YOUR ANSWER HERE
//
// A good choice of data structure in this case would be a hashmap so that you can link the
// ticker symbol to the current price. HashMaps have a put method that lets you rewrite over
// the current value that is set to the key

// Suppose you are building a music player application where users can create playlists.
// Songs can be added to the end of the playlist in the order the user chooses, and the user can
// skip to the next or previous song. Most operations involve adding songs and accessing them by
// their position in the playlist.
// What would be a good choice of data structure?
// YOUR ANSWER HERE
//
// A good choice of data structure for this problem would be an arrayList. That way you can store
// data and access it very easily, but the ArrayList can fluctate in size and appending another
// song at the end of the playlist would keep the time complexity relatively low.

// Suppose you are developing a search feature that keeps track of the user's
// recent search queries. You want to store the queries in the order they were made,
// so you can display them to the user for quick access. The number of recent searches is
// relatively small, and it is more important to preserve the order of the searches than
// to optimize for fast lookups or deletions.
// What would be a good choice of data structure?
// YOUR ANSWER HERE
//
// In this instance I would use a queue. Starting with the oldest searches and going up in
// how recent it is I would add each search to a queue. That way you would definitley be able
// preserve the order. Since we aren't worried about lookups or deletions, that takes away the
// few problems that using a queue creates.
}