模乘运算和模幂运算

2019-04-13 11:52发布

inline unsigned __int64 MulMod(unsigned __int64 a,unsigned __int64 b,unsigned __int64 n)//模乘运算即计算两个数的乘积然后取模
{
return (a % n)*(b % n )% n;
}

unsigned __int64 PowMod(unsigned __int64 base,unsigned __int64 pow,unsigned __int64 n)//模幂运算即首先计算某数的若干次幂,然后对其结果进行运算
{
unsigned __int64 a=base, b=pow, c=1;
while (b)
{
while( !(b & 1) )
{
b>>=1;
a= MulMod(a, a, n);
}
b--;
c=MulMod(a, c, n);
}
return c;
}