数论知识好多都忘记了，今天周末没啥事就复习一下

用扩展欧几里得算法

取地址不是很熟悉就用全局变量吧

#include<bits/stdc++.h>
using namespace std;
long long x, y;
void exgcd(long long a, long long b)
{
	if(b == 0) 
	{ 
		x = 1;
		y = 0;
		return;
	} 
	exgcd(b, a % b);
	long long tx = x;
	x = y;
	y = tx - a / b * y; 
}
int main()
{
	long long a, b;
	cin >> a >> b;
	exgcd(a, b);
	x = (x % b + b) % b;
	printf("%lld\n", x);
	return 0;
}