View Code of Problem 1056

#include<stdio.h>
#include<iostream>
#include<algorithm>
#include<stdlib.h>
#include<map>
#define LL long long
using namespace std;
double x[2010],y[2010];
struct s
{
    double x,y;
}a[1010*1010];
int cmp(s a, s b)
{
    if(a.x==b.x)
        return a.y<b.y;
    return a.x<b.x;
}
LL C(LL a,LL b)
{
    LL ans=1;
    LL i;
    while(b>a/2)
        b=a-b;
    for(i=1;i<=b;i++)
    {
        ans*=(a-i+1);
        ans/=i;
    }
    return ans;
}
int main()
{
    int t,c=0;
    scanf("%d",&t);
    while(t--)
    {
        int n;
        scanf("%d",&n);
        int i,j;
        for(i=1;i<=n;i++)
        {
            //double x,y;
            scanf("%lf%lf",&x[i],&y[i]);
        }
        int k=0;
        for(i=1;i<=n;i++)
            for(j=i+1;j<=n;j++)
            {
                if(x[i]==x[j]&&y[i]==y[j])
                    continue;
                double mx,my;
                mx=(x[i]+x[j])/2;
                my=(y[i]+y[j])/2;
                a[k].x=mx;
                a[k++].y=my;
            }
        sort(a,a+k,cmp);
        /*for(i=0;i<k;i++)
        {
            printf("****%lf %lf\n",a[i].x,a[i].y);
        }*/
        double tx,ty;
        LL temp=1,ans=0;
        for(i=1;i<k;i++)
        {
            if(a[i].x==a[i-1].x&&a[i].y==a[i-1].y)
            {
                temp++;
            }
            else
            {
                if(temp<2)
                {
                    temp=1;
                    continue;
                }
                ans+=C(temp,2);
                temp=1;
            }
        }
        if(temp>=2)
            ans+=C(temp,2);
        printf("Case %d: %lld\n",++c,ans);
    }
}