HDU ACM 1222 Wolf and Rabbit

原题描述

Problem Description

There is a hill with n holes around. The holes are signed from 0 to n-1.



A rabbit must hide in one of the holes. A wolf searches the rabbit in anticlockwise order. The first hole he get into is the one signed with 0. Then he will get into the hole every m holes. For example, m=2 and n=6, the wolf will get into the holes which are signed 0,2,4,0. If the rabbit hides in the hole which signed 1,3 or 5, she will survive. So we call these holes the safe holes.

Input

The input starts with a positive integer P which indicates the number of test cases. Then on the following P lines,each line consists 2 positive integer m and n(0<m,n<2147483648).

Output

For each input m n, if safe holes exist, you should output “YES”, else output “NO” in a single line.

Sample Input

2

1 2

2 2

Sample Output

NO

YES

解题思路

试验得出当m和n互质时，不存在安全的洞。所以本题可以转化为求最大公因数。

当最大公因数为1，则m和n互质，不存在安全洞；当最大公因数大于1，存在安全洞。

参考代码

/*
HDU ACM 1222 Wolf and Rabbit
Author: Scarb
2016-3-15
*/
#include <iostream>
using namespace std;
__int64 gcd(__int64 a, __int64 b)   // a > b
{
if (a < b)return gcd(b, a);
if (!b)return a;
return gcd(b, a%b);
}
int main()
{
int p;
__int64 m, n;
cin >> p;
while(p--)
{
cin >> m >> n;
if (gcd(m, n) == 1)cout << "NO\n";
else cout << "YES\n";
}
}