HDU 1757矩阵快速幂

#include <iostream>
#include <algorithm>
#include <cstdlib>
#include <cstring>
#include <string>
#include <vector>
#include <cstdio>
#include <queue>
#include <cmath>

using namespace std;

const int Max = 13;

struct Matrix{
        int  m[Max][Max];
} ;
Matrix I;
Matrix pag;
int n,M;

void init(int n){
    for(int i=1;i<=n;i++)
        I.m[i][i]=1;
}
void print(Matrix c){
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
            printf("%d ",c.m[i][j]);
        }
        printf("\n");
    }
}
           
Matrix matrixmul(Matrix a,Matrix b) //矩阵乘法
{
       int i,j,k;
       Matrix c;
       for (i = 1 ; i <= n; i++)
           for (j = 1; j <= n;j++)
             {
                 c.m[i][j] = 0;
                 for (k = 1; k <= n; k++)
                     c.m[i][j] += (a.m[i][k] * b.m[k][j])%M;
                 c.m[i][j] %= M;
             }
       return c;
}

Matrix quickpagow(int nn)
{
       Matrix m = pag, b = I;//b是单位矩阵
       while (nn >= 1)
       {
             if (nn & 1)
                b = matrixmul(b,m);
             nn = nn >> 1;
             m = matrixmul(m,m);
       }
       return b;
}

int main()
{
    int r;
    while(scanf("%d %d",&r,&M) == 2){
        n=10;
        init(n);
        if(r<=9){
            printf("%d\n",n);
            continue;
        }
        memset(pag.m,0,sizeof(pag.m));
        for(int i=1;i<=10;i++)
            scanf("%d",&pag.m[1][i]);
        for(int i=2;i<=10;i++){
            pag.m[i][i-1] = 1;
        }
        r=r-9;
        Matrix A = quickpagow(r);
        int ans=0;
        for(int i=1;i<=10;i++){
            ans += A.m[1][i] * (10-i);
            ans %= M;
        }
        printf("%d\n",ans);
    }
    return 0;
}