UVA 1152(p237)----4 Values Whose Sum is Zero

#include<cstdio>#include<iostream>#include<algorithm>using namespace std;long long ans,sum[16000000];int cas,a[5000],b[5000],c[5000],d[5000],n;int main(){    scanf("%d",&cas);    while(cas--)    {        scanf("%d",&n);        int num=0;ans=0;        for(int i=0;i<n;i++)            scanf("%d%d%d%d",&a[i],&b[i],&c[i],&d[i]);        for(int i=0;i<n;i++)            for(int j=0;j<n;j++)               sum[num++]=a[i]+b[j];         sort(sum,sum+num);        for(int i=0;i<n;i++)            for(int j=0;j<n;j++)               {                   long long temp=-c[i]-d[j];                   ans+=(upper_bound(sum,sum+num,temp)-lower_bound(sum,sum+num,temp));               }        printf("%lld\n",ans);        if(cas) puts("");    }    return 0;}