leetcode215. Kth Largest Element in an Array

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.

解法

维护长度为k的优先队列

public class Solution {
public int findKthLargest(int[] nums, int k) {
if (nums == null || nums.length == 0 || k > nums.length) {
return -1;
}

PriorityQueue<Integer> pq = new PriorityQueue<>();
for (int num : nums) {
pq.offer(num);
if (pq.size() > k) {
pq.poll();
}
}

return pq.peek();
}
}