Who‘s in the Middle

5
2
4
1
3
5

3

Hint
 
INPUT DETAILS: 

Five cows with milk outputs of 1..5 

OUTPUT DETAILS: 

1 and 2 are below 3; 4 and 5 are above 3.
 

就是奇数个数字，求中位数，排序下，即可

#include<iostream>
#include<stdio.h>
#include<string.h>
int a[10010];
using namespace std;
void Swap(int *a,int *b){
    int t=*a;
    *a=*b;
    *b=t;
}
int partition(int a[],int l,int h){
    int v = a[l];
    int i=l;
    int j=h+1;
    while(true){
        while(a[++i]<v)if(i==h)break;
        while(v<a[--j])if(j==l)break;
        if(i>=j)break;
        Swap(&a[i],&a[j]);
    }
    Swap(&a[l],&a[j]);
    return j;
}
void quick_sort(int a[],int l,int h){
    if(h<=l)return ;
    int j=partition(a,l,h);
    quick_sort(a,l,j-1);//左边
    quick_sort(a,j+1,h);//右边
}
int main(int argc, char *argv[])
{
    //freopen("1157.in","r",stdin);
    int N;
    int i;
    while(scanf("%d",&N)!=EOF)
    {
        i=0;
        for(i=0;i<N;++i)
            scanf("%d",&a[i]);
        quick_sort(a, 0, N-1);
        printf("%d\n",a[N/2]);
    }
    return 0;
}

HDU 1157 Who's in the Middle （快速排序 or 任意排序）

原文：http://blog.csdn.net/wdkirchhoff/article/details/41865579