@steveyg

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

#include #define MAXN 1000 #define offset 10000 #define eps 1e-8 #define PI acos(-1.0)//3.14159265358979323846 //判断一个数是否为0,是则返回true,否则返回false #define zero(x)(((x)>0?(x):-(x))<eps) //返回一个数的符号，正数返回1，负数返