正方形判断

正方形检测

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

struct node {
    int x,y;
    bool operator<(const node T)const {
        if(x!=T.x)return x<T.x;
        return y<T.y;
    }
};

int getlen(node a,node b) {
    return (a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y);
}

bool check(node a[]) {
    sort(a,a+4);
    int s[10];
    s[1]=getlen(a[0],a[1]);
    s[2]=getlen(a[0],a[2]);
    s[3]=getlen(a[0],a[3]);
    s[4]=getlen(a[1],a[2]);
    s[5]=getlen(a[1],a[3]);
    s[6]=getlen(a[2],a[3]);
    sort(s+1,s+1+6);
    return s[1]==s[4]&&s[5]==s[6];//对角线相等就可以了,double类型应该也是一样的
}

int main() {
    node a[4];
    for(int i=0;i<4;i++)cin>>a[i].x;
    for(int i=0;i<4;i++)cin>>a[i].y;
    if(check(a))cout<<"It's a square";
    else cout<<"Not a square";
    return 0;
}