[leetcode] 215. Kth Largest Element in an Array

题目：

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.

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.

思路：

1.先排序再找第k个

2.用优先队列，不用排序。

代码：

Python排序：

class Solution:
    def findKthLargest(self, nums, k):
        """
        :type nums: List[int]
        :type k: int
        :rtype: int
        """
        nums.sort(reverse=True)
        return nums[k-1]

C++：堆：

#include<queue>
class Solution {
public:
    int findKthLargest(vector<int>& nums, int k) {
        priority_queue<int> que;
        for(int i = 0; i < nums.size(); i++){
            que.push(nums[i]);
        }
        for(int i = 0; i < k - 1; i++){
            que.pop();
        }
        return que.top();
    }
};