一、题目内容

二、题解

解法1：

思路

代码

public class Solution {
    public int findKth(int[] a, int n, int K) {
        //边界条件
        return quickFind(a, 0, n - 1, K);
    }
    private int quickFind(int[] a, int left, int right, int k) {
        int p = partition(a,left,right);
        if (p == k - 1) {
            return a[p];
        } else if (p > k - 1) {
            return quickFind(a, left, p-1, k);
        } else {
            return quickFind(a, p+1,right, k);
        }
    }
    private int partition(int[] a, int left, int right){
        int target = a[left];
        while (left < right) {
            while (left < right && a[right] <= target) {
                right--;
            }
            if (left < right) {
                a[left] = a[right];
                left++;
            }
            while (left < right && a[left] > target) {
                left++;
            }
            if (left < right) {
                a[right] = a[left];
                right--;
            }
        }
        a[left] = target;
        return left;
    }
}