Dancing Stars on Me---hdu5533（判断是否为正多边形）

#include<stdio.h>
#include<string.h>
#include<algorithm>
#include<iostream>
#include<vector>
#include<queue>
#include<set>
using namespace std;
#define met(a, b) memset(a, b, sizeof(a))
#define N 105
#define INF 0x3f3f3f3f
typedef long long LL;

int d[N*N], x[N], y[N];

int main()
{
    int T, n;
    scanf("%d", &T);
    while(T--)
    {
        met(d, 0);
        int k = 0;
        scanf("%d", &n);
        for(int i=1; i<=n; i++)
        {
            scanf("%d %d", &x[i], &y[i]);
            for(int j=1; j<i; j++)
            {
                d[k++] = (x[i]-x[j])*(x[i]-x[j]) + (y[i]-y[j])*(y[i]-y[j]);
            }
        }
        sort(d, d+k);
        int len = unique(d, d+k)-d;
        if(len == n/2)
            printf("YES\n");
        else
            printf("NO\n");
    }
    return 0;
}