LeetcodeKth Largest Element in an Array

Posted 2020-07-19 wuezs

题目链接：https://leetcode.com/problems/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.

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.

思路：

1、快排，时间复杂度O(nlogn)

2、分冶..用快排划分，递归的划分。每一次划分都可以去确定一个元素的位置，也就知道比该元素小的元素数目。目测时间复杂度最差为 O(n^2)，最好为O(1)，平均？没动力做了......待做

算法：

public int findKthLargest(int[] nums, int k) {  
    Arrays.sort(nums);  
    return nums[nums.length-k];  
}