HDU 4335 Contest 4

利用降幂公式。。呃，还是自己去搜题解吧。知道降幂公式后，就不难了。

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#define LL unsigned long long 
using namespace std;

bool mod[100005];

LL PHI(LL P){
    LL ret=1;  
    for(LL i=2;i*i<=P;i++)  
        if(P%i==0){  
            ret*=i-1;  
            P/=i;  
            while(P%i==0){  
                P/=i;  
                ret*=i;  
            }  
        }  
    if(P>1)  
        ret*=P-1;  
    return ret; 
}

LL quick(LL a,LL k,LL m){
	LL ret=1; LL t=a%m;
	while(k){
		if(k&1) ret=(ret*t)%m;
		k>>=1;
		t=(t*t)%m;
	}
	return ret;
}

int main(){
	int T;
	LL b,P,M;
	scanf("%d",&T);
	for(int kase=1;kase<=T;kase++){
		scanf("%I64u%I64u%I64u",&b,&P,&M);
		printf("Case #%d: ",kase);
        if(P==1){  
            if(M==18446744073709551615ULL)  
                printf("18446744073709551616\n");         
            else                  
                printf("%I64u\n",M+1);  
            continue;  
        }
		LL phi=PHI(P);
		LL i,ans;
		LL fac=1; ans=0;
		for(i=0;i<=M&&fac<=phi;i++){
			if(quick(i,fac,P)==b){
				ans++;
			}
			fac*=(i+1);
		}
		fac%=phi;
		for(;i<=M&&fac;i++){
			if(quick(i,fac,P)==b)
			ans++;
			fac=(fac*(i+1))%phi;
		}
		if(i<=M){
			memset(mod,false,sizeof(mod));
			LL cn=0;
			for(LL k=0;k<P;k++){
				if(quick(i+k,phi,P)==b){
					mod[k]=true;
					cn++;
				}
			}
			ans+=((M-i+1)/P)*cn;
			LL e=(M-i+1)%P;
			for(LL k=0;k<e;k++)
			if(mod[k])
			ans++;
		}
		printf("%I64u\n",ans);
	}
	return 0;
}