neetcode-gh · mitchellirvin · Jul 11, 2022 · Apr 26, 2022 · Jul 11, 2022 · Jul 11, 2022
diff --git a/javascript/217-Contains-Duplicate.js b/javascript/217-Contains-Duplicate.js
@@ -2,6 +2,8 @@
  * @param {number[]} nums
  * @return {boolean}
  */
+
+//First method using Map() (exit early if true)
 var containsDuplicate = function(nums) {
     const numsSet =  new Set()
     for(const i of nums){
@@ -10,5 +12,20 @@ var containsDuplicate = function(nums) {
         } 
         numsSet.add(i)
     }
-    return false
-};
+    return false;
+};
+
+//Second method using Map() (Has to map entire array but code is more readable)
+var containsDuplicate = function(nums) {
+    //create a new hashmap with all the items in the array. Any duplicates will be removed.
+    const totalWithoutDuplicates = new Map(nums.map((i) => [i]));
+
+    //check if the size of the initial array is larger than the new hashmap. 
+    return totalWithoutDuplicates.size !== nums.length;
+};
+
+//Third method using Set() (Fastest runtime at 91.95% and very readable code)
+var containsDuplicate = function(nums) {
+    //Pass the array into a Set() (which removes duplicates) and then compare its size to the original array. 
+    return new Set(nums).size !== nums.length;
+};