diff --git a/src/Main.java b/src/Main.java
index 036c766..628e81d 100644
--- a/src/Main.java
+++ b/src/Main.java
@@ -7,6 +7,7 @@ public class Main {
 
   // The time complexity is:
   // YOUR ANSWER HERE
+  //o(x^2)
   public static void timesTable(int x) {
     for(int i = 1; i <= x; i++) {
         for(int j = 1; j <= x; j++) {
@@ -18,6 +19,7 @@ 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();
 
@@ -28,6 +30,7 @@ public static void printLetters(String word) {
 
   // The time complexity is:
   // YOUR ANSWER HERE
+  //o(1)
   public static boolean isBanned(String password) {
     String[] bannedPasswords = {"password", "hello", "qwerty"};
     boolean banned = false;
@@ -42,6 +45,7 @@ public static boolean isBanned(String password) {
 
   // The time complexity is:
   // YOUR ANSWER HERE
+  //o(n)
   public static int computeProduct(int[] nums) {
     int total = 1;
     for(int num : nums) {
@@ -52,6 +56,7 @@ 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);
@@ -61,6 +66,8 @@ 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++) {
@@ -71,6 +78,7 @@ public static int computeFactorial(int n) {
 
   // Assume that the largest number is no bigger than the length
   // of the array
+  //o(n^2)
   public static void computeAllFactorials(int[] nums) {
     for(int num : nums) {
         int result = computeFactorial(num);
@@ -82,6 +90,7 @@ public static void computeAllFactorials(int[] nums) {
   // assume that each String is bounded by a constant length
   // The time complexity is:
   // YOUR ANSWER HERE
+  // o(n)
   public static void checkIfContainedArrayList(ArrayList<String> arr, String target) {
     if (arr.contains(target)) {
         System.out.println(target + " is present in the list");
@@ -95,6 +104,7 @@ public static void checkIfContainedArrayList(ArrayList<String> arr, String targe
   // assume that each String is bounded by a constant 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) {
@@ -109,6 +119,7 @@ public static boolean containsOverlap(String[] wordsA, String[] wordsB) {
   // assume that each String is bounded by a constant length
   // 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) {
@@ -126,14 +137,16 @@ public static boolean containsOverlap2(String[] wordsA, String[] wordsB) {
 
   // The time complexity is:
   // YOUR ANSWER HERE
+  //o(n)
   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:
+  // The time complexity is
   // YOUR ANSWER HERE
+  //o(1)
   public static double computeAverage(double a, double b) {
     return (a + b) / 2.0;
   }
@@ -141,6 +154,7 @@ public static double computeAverage(double a, double b) {
   // assume that each String is bounded by a constant length
   // The time complexity is:
   // YOUR ANSWER HERE
+  //o(1)
   public static void checkIfContainedHashSet(HashSet<String> set, String target)
   {
     if (set.contains(target)) {
@@ -155,8 +169,9 @@ 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"
   // assume that each String is bounded by a constant length
-  // What is the time complexity of this method?
+  // What is the time complexity of this method? 
   // YOUR ANSWER HERE
+  //o(n)
   public static String emailLookup(String[] names, String[] emails, String queryName) {
     for(int i = 0; i < names.length; i++) {
       if (names[i].equals(queryName)) {
@@ -173,14 +188,16 @@ public static String emailLookup(String[] names, String[] emails, String queryNa
   // assume that each String is bounded by a constant length
   // 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;
+    return namesToEmails.getOrDefault(queryName, "Person not found");
   }
 
   // What is the time complexity of this method?
   // assume that each String is bounded by a constant length
   // (assume the set and list have the same number of elements)
   // YOUR ANSWER HERE
+  // o(n^2)
   public static boolean hasCommon(HashSet<String> wordSet, ArrayList<String> wordList) {
     for(String word : wordSet) {
       if(wordList.contains(word)) {
@@ -192,18 +209,31 @@ public static boolean hasCommon(HashSet<String> wordSet, ArrayList<String> wordL
   // Rewrite hasCommon so it does the same thing as hasCommon, but with a better time complexity.
   // Do not change the datatype of wordSet or wordList.
   // assume that each String is bounded by a constant length
-  // What is the time complexity of your new solution?
+  // What is the time complexity of your new solution?  
   // YOUR ANSWER HERE
+  //o(n+m)
   public static boolean hasCommonEfficient(HashSet<String> wordSet, ArrayList<String> wordList) {
-    return false;
+      // Create a HashSet from wordList for O(1) lookups
+      HashSet<String> wordListSet = new HashSet<>(wordList);
+
+      // Check if any word in wordSet is in wordListSet
+      for (String word : wordSet) {
+          if (wordListSet.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
+  //HashMap
+
 
   // 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
@@ -211,6 +241,8 @@ public static boolean hasCommonEfficient(HashSet<String> wordSet, ArrayList<Stri
   // their position in the playlist.
   // What would be a good choice of data structure?
   // YOUR ANSWER HERE
+  //ArrayList
+  
 
   // 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,
@@ -219,4 +251,5 @@ public static boolean hasCommonEfficient(HashSet<String> wordSet, ArrayList<Stri
   // to optimize for fast lookups or deletions.
   // What would be a good choice of data structure?
   // YOUR ANSWER HERE
+  //ArrayListe
 }
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