View Code of Problem 1056

#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;
struct node
{
    int x,y;
};
node point[1010];
node mid[1010*1010];

int cmp(node A,node B)
{
    if(A.x==B.x)
        return A.y<B.y;
    return A.x<B.x;
}

int main()
{
    int t;
    int i,j;
    int sum;
    int n;
    int cnt;int k=0;
    scanf("%d",&t);
    while(t--)
    {
        scanf("%d",&n);
        sum=0;
        cnt=0;
        for(i=0;i<n;i++)
            scanf("%d%d",&point[i].x,&point[i].y);
        for(i=0;i<n;i++)
            for(j=i+1;j<n;j++)
            {
                mid[cnt].x=(point[i].x+point[j].x);
                mid[cnt].y=(point[i].y+point[j].y);
                cnt++;
            }
        sort(mid,mid+cnt,cmp); //中点排序//对于一个平行四边形，其两条对角线的的交点是其中点。因此可以计算每条线段的中点是否相等判断是否相等
        int count=1;
        
        for(i=0;i<cnt;i++)
        {
            if(mid[i].x==mid[i+1].x&&mid[i].y==mid[i+1].y)
                count++;
            else
            {
                sum+=(count-1)*count/2;
                count=1;
            }
        }
        printf("Case %d: ",++k);
        printf("%d\n",sum);
    }
    return 0;
}