add kth largest element in an array

Author: chihungyu1116

215 Kth Largest Element in an Array.js

@@ -0,0 +1,33 @@
+/**
+ * @param {number[]} nums
+ * @param {number} k
+ * @return {number}
+ */
+ 
+//  use quick select
+var findKthLargest = function(nums, k) {
+    var smaller = [];
+    var larger = [];
+    var pivot = nums[parseInt(nums.length/2)];
+    var pivotCnt = 0;
+    
+    for(var i = 0; i < nums.length; i++) {
+        var num = nums[i];      
+      
+        if(num > pivot) {
+            larger.push(num);
+        } else if(num < pivot) {
+            smaller.push(num);
+        } else {
+            pivotCnt++;
+        }
+    }
+      
+    if(k <= larger.length) { // if larger includes k
+        return findKthLargest(larger, k);
+    } else if(k - larger.length - pivotCnt <= 0) { // k is part of pivot
+        return pivot;
+    } else { // if smaller inclues k
+        return findKthLargest(smaller, k - larger.length - pivotCnt);
+    }
+};