Wannafly挑战赛26

#include <bits/stdc++.h>
using namespace std;

typedef long long LL;
#define MAX_N 1100
int n;

struct Point{
    LL x,y;
}p[MAX_N];

LL d[MAX_N][MAX_N];

LL dis(Point a, Point b){
    return (a.x - b.x)*(a.x - b.x)*1LL + (a.y - b.y) * (a.y - b.y)*1LL;
}

int main(){
   // freopen("in.txt", "r", stdin);
    ios::sync_with_stdio(0); cin.tie(0);
    cin >> n;
    for(int i = 0; i < n; ++i){
        cin >> p[i].x >> p[i].y;
    }
    for(int i = 0; i < n; ++i){
        for(int j = 0; j < n; ++j){
            if(i == j) continue;
            d[i][j] = dis(p[j], p[i]);
        }
    }
    for(int i = 0; i < n; ++i){
        LL ans;
        ans = (i == 0) ?  d[i][1] : d[i][0];
        int j;
        for(j = 0; j < n; ++j){
            if(j == i) continue;
            if(ans != d[i][j]) break;
        }
        if(j == n) {
            cout << i+1;
            return 0;
        }
    }
    cout << "-1";
    return 0;
}