模板—十进制快速幂

#include<iostream>
#include<cstring>
#include<cstdio>
#define LL long long
using namespace std;
char c[100000];
LL a,p,t;
LL tenthpow(LL a)
{
	LL ans=1,s=a;
	while(t>=0)
	{
		LL cnt=c[t]-‘0‘,cur=s;
		for(int i=1;i<=cnt;i++)
		ans=ans*s%p;
		for(int i=1;i<10;i++)
		cur=cur*s%p;
		s=cur;ans%=p;t--;
	}
	return ans;
}
signed main()
{
	cin>>a>>c>>p;
	t=strlen(c);t--;
	cout<<tenthpow(a)<<endl;
}