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
        return quick_search(a,0,n-1,K,n);
    }

    int quick_search(int[] a,int low,int high,int K,int n){
        int left=low;
        int right=high;
       // System.out.println("left:"+left);
       // System.out.println("right:"+right);
        if(left>right) return -1;
        int base=left;
        int temp=a[base];

        while(left<right){
            while(left<right&&a[right]>=temp){
                right--;
                 //System.out.println("22:");
            }
            while(left<right&&a[left]<=temp){
                 //System.out.println("11:");
                left++;
            }
            if(left<right){
                int b=a[left];
                a[left]=a[right];
                a[right]=b;
            }

        }

        //System.out.println("left:"+left);
         //System.out.println("right:"+right);
        a[base]=a[left];
        a[left]=temp;
        //System.out.println("di ji xiao :"+(n-K));
        if(left==(n-K)){
            return temp;
        }
        else if(left<(n-K)){
            
            return quick_search(a,left+1,high,K,n);
        }
        else{
            return quick_search(a,low,left-1,K,n);
        }

        



    }
}