[POJ 2356] Find a multiple

#include<iostream>
#include<cstdlib>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
using namespace std;
#define N 10010

struct Node
{
    int x,y,s; //下标,余数,前缀和
    bool operator <(const Node &t)const
    {
        if(y!=t.y) return y<t.y;
        return x<t.x;
    }
}p[N];

int main()
{
    int n;
    int flag;
    int a[N];
    while(scanf("%d",&n)!=EOF)
    {
        flag=0;
        for(int i=1;i<=n;i++)
        {
            scanf("%d",&a[i]);
            p[i].s=p[i-1].s+a[i];
            p[i].x=i;
            p[i].y=p[i].s%n;
            if(!flag && p[i].y==0)
            {
                flag=1;
                printf("%d\n",i);
                for(int j=1;j<=i;j++) printf("%d\n",a[j]);
            }
        }
        if(flag) continue;
        sort(p+1,p+n+1);
        for(int i=2;i<=n;i++)
        {
            if(p[i].y==p[i-1].y)
            {
                int &l=p[i-1].x;
                int &r=p[i].x;
                printf("%d\n",r-l);
                for(int j=l+1;j<=r;j++) printf("%d\n",a[j]);
                break;
            }
        }
    }
    return 0;
}