Kth largest

Author: EndaLin

solution/0215.Kth Largest Element in an Array/Solution.java

@@ -1,17 +1,25 @@
 class Solution {
     public int findKthLargest(int[] nums, int k) {
-        PriorityQueue<Integer> minHeap = new PriorityQueue<>(k);
-        for (int e : nums) {
-            if (minHeap.size() < k) {
-                minHeap.add(e);
-            } else {
-                if (minHeap.peek() < e) {
-                    minHeap.poll();
-                    minHeap.add(e);
-                }
+        return find(nums, 0, nums.length - 1, k - 1);
+    }
+    
+    private int find(int[] nums, int left, int right, int k) {
+        int i = left;
+        int j = right;
+        int index = nums[left];
+        while (i < j) {
+            while (i < j && index >= nums[j]) j--;
+            if (i < j) {
+                nums[i++] = nums[j];
+            }
+            while (i < j && index <= nums[i]) i++;
+            if (i < j) {
+                nums[j--] = nums[i];
             }
-            
         }
-        return minHeap.peek();
+        nums[i] = index;
+        if (i > k) return find (nums, left, i - 1, k);
+        else if (i < k) return find(nums, i + 1, right, k);
+        else return nums[i];
     }
 }