九度OJ 二分求幂法、快速取模之《root(n,k)》

借鉴http://blog.sina.com.cn/s/blog_8619a25801010wcy.html

题目地址：http://ac.jobdu.com/problem.php?pid=1085

//九度OJ 快速取模之《root(n,k)》
//http://ac.jobdu.com/problem.php?pid=1085
#include<stdio.h>
int k;
long fang(long a,long b)
{
	long long ret=1;
	while(b)
	{
		if(b&1)ret=ret*a%(k-1);
		a=a*a%(k-1);
		b>>=1;
	}
	return ret;
}
int main()
{
	long long x,y;
	int i;
	while(~scanf("%lld %lld %d",&x,&y,&k))
	{
		long ret=fang(x,y);
		if(!ret)ret=k-1;
		printf("%lld\n",ret);
	}
	return 0;
}