Timus 1286

分析

详见这篇非常好的分析
AC代码：

#include <bits/stdc++.h>

using namespace std;

#define LL long long

LL gcd(LL a, LL b){
    return b ? gcd(b, a%b):a;
}

int main(){
    bool ans = true;
    LL p, q;
    LL x1, y1, x2, y2;
    LL dx, dy;
    cin >>p >>q;
    cin >>x1 >>y1 >>x2 >>y2;

    dx = x2-x1, dy = y2-y1;
    LL gd = gcd(p, q);

    if(dx % gd!=0 || dx%gd !=0){
        ans = false;
    }
    else{
        dx /= gd, dy /= gd;
        p /= gd, q /= gd;
        if(abs(dx%2) == abs(dy%2) || (abs(dx%2) != abs(dy%2) && abs(p%2) != abs(q%2)) )
            ans = true;
        else
            ans = false;
    }

    if(ans ) cout <<"YES\n";
    else cout <<"NO\n";

    return 0;
}