Codeforces Round #287 D.The Maths Lecture

#include <bits/stdc++.h>
using namespace std;
#define ll long long
int n, k, MOD;
ll f[1009][109], tem = 1, ans, tot = 9;
int main() {
       ios::sync_with_stdio(0);
    cin >> n >> k >> MOD;
    for (int i = 1; i <= n; i++) {
        for (int j = 0; j < k; j++) {
            for (int t = 0 + (i == n); t <= 9; t++) {
                ll d = (t * tem + j) % k;
                if (d) f[i][d] += f[i - 1][j] + (j == 0);
                if (f[i][d] >= MOD) f[i][d] -= MOD;
            }
        }
        tem = (tem * 10) % k;
    }
    for (int i = 1; i < n; i++) tot *= 10, tot %= MOD;
    for (int i = 1; i < k; i++) ans += f[n][i], ans %= MOD;
    cout << (MOD + tot - ans) % MOD << endl;
    return 0;
}