题解 | #寻找第K大#

import java.util.*;


public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param a int整型一维数组
     * @param n int整型
     * @param K int整型
     * @return int整型
     */
    public int findKth (int[] a, int n, int K) {
        // write code here
        int left = 0;
        int right = a.length - 1;

        quickSort(a,  left,  right);

        return a[a.length - K];
    }

    private void quickSort(int[] a, int start, int end) {

        int left = start;
        int right = end;

        if (left >= right) {
            return;
        }

        int res  = a[left];
        while (left < right) {

            while (left < right && res <= a[right]) {
                right--;
            }
            swap( a,  left,  right);
            while (left < right && a[left] <= res) {
                left++;
            }
            swap( a,  left,  right);
        }

        quickSort( a, start, left - 1);
        quickSort(a, left + 1, end);
    }

    private void swap(int[] a, int left, int right) {
        int temp = a[left];
        a[left] = a[right];
        a[right] = temp;
    }
}