215. Kth Largest Element in an Array

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.

Solution first. remain a min-heap of size k, if size exceed k, pop the top value.

public class Solution {
    public int findKthLargest(int[] nums, int k) {
        PriorityQueue<Integer> pq = new PriorityQueue<Integer>();
        for(int i : nums){
            pq.add(i);
            if(pq.size() > k ) pq.poll();
        }

        return pq.poll();
    }
}

Java's PriorityQueue implementation allows duplicates instance of same value been added,

To have non-duplicate PriorityQueue, you need to override PriorityQueue's offer/add function.