扩展欧几里得算法

扩展欧几里得  ax + by = gcd( a,b ) = n

 

int extgcd(int a,int b,int &x,int &y){int d = a;if( b != 0){d = extgcd(b,a % b,y, x);y -= (a / b) * x;}else {x = 1;y = 0;}return d;}