hdu 4549 (矩阵快速幂+费马小定理)

#include <iostream>
#include <cmath>
#include <cstdio>
#define ll long long
#define MOD 1000000007

using namespace std;

const int N=2,M=2,P=2;

ll qmod(ll a,ll b,ll mod)
{
    ll ans=1;
    a=a%mod;
    while(b)
    {
        if(b&1)
        {
            ans=(ans*a)%mod;
        }
        b=b/2;
        a=(a*a)%mod;
    }
    return ans;
}

struct Matrix
{
    ll m[N][N];
};

Matrix A={1,1,
          1,0};

Matrix I={1,0,
          0,1};

Matrix mult(Matrix a,Matrix b,ll mod)
{
    Matrix ans;
    for(int i=0;i<N;i++)
    {
        for(int j=0;j<M;j++)
        {
            ans.m[i][j]=0;
            for(int k=0;k<P;k++)
            {
                ans.m[i][j]+=(a.m[i][k]*b.m[k][j])%mod;
            }
            ans.m[i][j]%=mod;
        }
    }
    return ans;
}

Matrix power(Matrix a,ll b,ll mod)
{
    Matrix ans=I,p=a;
    while(b)
    {
        if(b&1)
        {
            ans=mult(ans,p,mod);
        }
        b=b/2;
        p=mult(p,p,mod);
    }
    return ans;
}

int main()
{
    ll a,b,n;
    while(cin>>a>>b>>n)
    {
        ll aa,bb;
        Matrix ans=power(A,n-1,MOD-1);
        bb=ans.m[0][0];
        aa=ans.m[1][0];
        a=a%MOD;
        b=b%MOD;
        if(n==0) bb=0;
        ll ans1=qmod(a,aa,MOD);
        ll ans2=qmod(b,bb,MOD);
        ll num=(ans1*ans2)%MOD;
        cout<<num<<endl;
    }
    return 0;
}