Codeforces Round #432 (Div. 2, based on IndiaHacks Final Round 2017) B. Arpa and an exam about geometry

题意：给出三个点A,B,C，问是否存在一个点，使得 A转到 B，B转到C 

思路：即AB==AC并且三点不共线

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

int main(){
    ll ax,ay;
    ll bx,by;
    ll cx,cy;
    cin>>ax>>ay>>bx>>by>>cx>>cy;
    ll s1=(ax-bx)*(ax-bx)+(ay-by)*(ay-by);
    ll s2=(cx-bx)*(cx-bx)+(cy-by)*(cy-by);
if((ax-bx)*(cy-by)==(ay-by)*(cx-bx)){
        cout<<"No"<<endl;return 0;
    }
    if(s1==s2){
        cout<<"Yes"<<endl;
    }
    else cout<<"No"<<endl;
}