Find the kth largest element in an unsorted array. Note that it is the kth largest element in the sorted order, not the kth distinct element.

For example,

Given [3,2,1,5,6,4] and k = 2, return 5.

Note: 

You may assume k is always valid, 1 ≤ k ≤ array's length

题目含义：求给定的数组中，前k大个数

1     public int findKthLargest(int[] nums, int k) { 2 //        final int N = nums.length; 3 //        Arrays.sort(nums); 4 //        return nums[N - k]; 5         PriorityQueue
     
       pq = new PriorityQueue<>(); 6         for (int i = 0; i < nums.length; i++) { 7             pq.offer(nums[i]); 8             if (pq.size() > k) pq.poll(); 9         }10         return pq.peek();        11     }