hdu 5451 Best Solver（矩阵快速幂+循环节)

#include <cstdio>
#include <iostream>
#include <cmath>
#include <algorithm>
#define ll long long

using namespace std;

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

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


Matrix A= {5,12,
           2,5
          };

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

Matrix multi(Matrix a,Matrix b)
{
    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 k)
{
    Matrix ans=I,p=a;
    while(k)
    {
        if(k&1)
        {
            ans=multi(ans,p);
        }
        k=k/2;
        p=multi(p,p);
    }
    return ans;
}

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;
}

int main(int argc, char const *argv[])
{
    int t,cas=1,n;
    cin>>t;
    while(t--)
    {
        cin>>n>>MOD;
        cout<<"Case #"<<cas++<<": ";
        n=qmod(2,n,(MOD*MOD-1))+1;
        Matrix ans=power(A,n-1);
        ll xn=(5*ans.m[0][0]+2*ans.m[0][1])%MOD;
        cout<<(2*xn-1)%MOD<<endl;
    }
    return 0;
}