HDU4549 M斐波那契数列

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cstring>
using namespace std;

typedef long long LL;
const int MOD = 1000000007;
struct Matrix{
   LL mat[2][2];
   LL row,col;
   Matrix(){};
   Matrix(LL _r,LL _c):row(_r),col(_c){};
};

Matrix I(2,2),P(2,2);

void Init(){
    P.mat[0][0] = 0;
    P.mat[0][1] = P.mat[1][0] = P.mat[1][1] = 1;

    I.mat[0][0] = I.mat[1][1] = 1;
    I.mat[0][1] = I.mat[1][0] = 0;
}

//矩阵相乘
Matrix mul(Matrix A,Matrix B,LL mod){
    Matrix C(2,2);
    memset(C.mat,0,sizeof(C.mat));

    for(int i = 0;i < A.row;++i){
        for(int k = 0;k < B.row;++k){
            for(int j = 0;j < B.col;++j){
                C.mat[i][j] = (C.mat[i][j] + A.mat[i][k] * B.mat[k][j] % mod) % mod;
            }
        }
    }
    return C;
}

//fib[n] % (c - 1)
Matrix powmod(Matrix A,LL n,LL mod){
     Matrix B = I;
     while(n > 0){
        if(n & 1) B = mul(B,A,mod);
        A = mul(A,A,mod);
        n >>= 1;
     }
     return B;
}

//a ^ b % c
LL powmod(LL a,LL n,LL mod){
   LL res = 1;
   while(n > 0){
       if(n & 1) res = (res * a) % mod;
       a = a * a % mod;
       n >>= 1;
   }
   return res;
}

int main()
{
    Init();
    LL a,b,n;
    while(~scanf("%I64d%I64d%I64d",&a,&b,&n)){
         Matrix A = powmod(P,n,MOD - 1);       //fib[n] % (mod -1 )
         printf("%I64d\n",powmod(a,A.mat[0][0],MOD) * powmod(b,A.mat[1][0],MOD) % MOD);
    }
    return 0;
}