HDU 1757 A Simple Math Problem

#include <iostream>
#include <cstdio>
#include <cstring>
#define REP(i, s, n) for(int i = s; i <= n; i ++)
#define REP_(i, s, n) for(int i = n; i >= s; i --)
#define MAX_N 10 + 5

using namespace std;

int k, m;
struct node{
    int Mtx[MAX_N][MAX_N];
}med;

void Pre_Set(){
    REP(i, 1, 10) scanf("%d", &med.Mtx[1][i]);
    REP(i, 2, 10) REP(j, 1, 10){
        if(i - j == 1) med.Mtx[i][j] = 1;
        else med.Mtx[i][j] = 0;
    } 
}

node operator*(node a,node b){
    node c;
    REP(i, 1, 10) REP(j, 1, 10){
        c.Mtx[i][j] = 0;
        REP(k, 1, 10) c.Mtx[i][j] += a.Mtx[i][k] * b.Mtx[k][j]; 
        c.Mtx[i][j] %= m;
    }
    return c;
}

node operator^(node a,int k){
    if(k == 0){
        memset(a.Mtx, 0, sizeof(a.Mtx));
        REP(i, 1, 10) a.Mtx[i][i] = 1;
        return a;
    }
    if(k == 1) return a;
    node c = a ^ (k >> 1);
    if(k & 1) return c * c *a;
    return c * c;
}

int main(){
    while(scanf("%d%d", &k, &m) != EOF){
        Pre_Set();
        if(k < 10) { cout << k % m << endl; }
        else {
            med = med ^ (k - 9);
            int ans = 0;
            REP(i, 1, 10){
                ans = (ans + med.Mtx[1][i] * (10 - i)) % m;
            }
            printf("%d\n", ans);
        }
    }
    return 0;
}