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;
}