模取幂(1).cpp

数值计算的例子和参考书籍

int powermod(int a, int s, int m)//a ^ s % m
{
	int t = 1, b = a;
	while(s > 0)
	{
		if((s & 1) == 1)
		{
			t = t * b % m;
		}
		b = b * b % m;
		s = s >> 1;
	}
	return t;
}