扩展欧几里得内容梗概对于任意两个数$a, b$,两者间必有最大公因子$g$,使得$a = k_1g,b = k_2g$ ;
可得必有整数$x, y$ 使$ax + by = gcd(a,b)$
板子typedef long long ll
2021-10-27