215 Kth Largest Element in an Array

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

Example 1:

Input:
[3,2,1,5,6,4] 
and k = 2

Output:
 5

Example 2:

Input:
[3,2,3,1,2,4,5,5,6] 
and k = 4

Output:
 4

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

First Method: PriorityQueue

class Solution {
    public int findKthLargest(int[] nums, int k) {
        if (nums == null || nums.length == 0) {
            return 0;
        }
        PriorityQueue<Integer> queue = new PriorityQueue<>();
        for (int i = 0; i < nums.length; i++) {
            queue.offer(nums[i]);
            if (queue.size() > k) {
                queue.poll();
            }
        }
        return queue.poll();
    }
}