zoj 2540 Form a Square

#include <iostream>#include <cmath>#include <algorithm>using namespace std;struct Node{    double x, y;}node[5];bool Cmp(const Node &a, const Node &b){    if(a.x == b.x)       return a.y < b.y;    return a.x < b.x;}double Distance(int i, int j){    return (node[i].x-node[j].x)*(node[i].x-node[j].x) + (node[i].y-node[j].y)*(node[i].y-node[j].y);}bool SameEdge(int i, int j, int k, int r){    double len1 = Distance(i, j);    double len2 = Distance(j, k);    double len3 = Distance(k, r);    double len4 = Distance(r, i);    double len23 = Distance(j, r);    if(len1==len2 && len2==len3 && len3==len4 && len2+len3 == len23)       return 1;    return 0;}int main(){#ifndef ONLINE_JUDGE    freopen("in", "r", stdin);#endif    int nCase, t=0;    cin >>nCase;    while(nCase--){       for(int i=0; i<4; i++)cin >>node[i].x >>node[i].y;       sort(node, node+4, Cmp);       if(t++)cout <<endl;       cout <<"Case " <<t <<":" <<endl;       if(SameEdge(0, 1, 3, 2))cout <<"Yes" <<endl;       elsecout <<"No" <<endl;    }    return 0;}