Update 0219-contains-duplicate-ii.js

Shortens and simplifies current solution by changing hashmap into a hashset.

Author: HunterHester

javascript/0219-contains-duplicate-ii.js

@@ -3,26 +3,24 @@
  * @param {number} k
  * @return {boolean}
  */
-var containsNearbyDuplicate = function (nums, k) {
-    let leftPtr = 0;
-    let rightPtr = 0;
-    let windowHashMap = new Map();
-    while (rightPtr < nums.length) {
-        if (windowHashMap.has(nums[rightPtr])) {
-            return true;
+/**
+ * @param {number[]} nums
+ * @param {number} k
+ * @return {boolean}
+ */
+var containsNearbyDuplicate = function(nums, k) {
+    const window = new Set();
+    let L = 0;
+    for(let R = 0; R < nums.length; R++){
+        if(!window.has(nums[R])){
+            window.add(nums[R]);
         } else {
-            windowHashMap.set(nums[rightPtr], 1);
+            return true
         }
-        rightPtr++;
-        if (rightPtr - leftPtr > k) {
-            let leftPtrValue = windowHashMap.get(nums[leftPtr]);
-            leftPtrValue--;
-            if (leftPtrValue == 0) {
-                windowHashMap.delete(nums[leftPtr]);
-            } else {
-                windowHashMap.set(nums[leftPtr], leftPtrValue);
-            }
-            leftPtr++;
+
+        if(R - L + 1 > k){
+            window.delete(nums[L])
+            L++;
         }
     }
     return false;