abc237f WA

// Problem: F - |LIS| = 3
// Contest: AtCoder - AtCoder Beginner Contest 237
// URL: https://atcoder.jp/contests/abc237/tasks/abc237_f
// Memory Limit: 1024 MB
// Time Limit: 2000 ms
//
// Powered by CP Editor (https://cpeditor.org)

#include <assert.h>
#include <bits/stdc++.h>
using namespace std;
#define dbg(...) logger(#__VA_ARGS__, __VA_ARGS__)
template <typename... Args> void logger(string vars, Args &&... values)
{
    cerr << vars << " = ";
    string delim = "";
    (..., (cerr << delim << values, delim = ", "));
    cerr << endl;
}

template <class T> using mpq = priority_queue<T, vector<T>, greater<T>>;
using ll = long long;
using pii = pair<int, int>;

int n, m;
ll mod = 998244353;

int main(int argc, char **argv)
{
    cin >> n >> m;
    int b = m + 1;
    int state = b * b * b;
    vector<vector<ll>> dp(n + 1, vector<ll>(state));
    dp[0][0] = 1;
    for (int i = 1; i <= n; ++i) {
        for (int j = 0; j < state; ++j) {
            if (dp[i - 1][j]) {
                int a1 = j % b;
                int a2 = (j / b) % b;
                int a3 = (j / b / b) % b;
                for (int k = 1; k < b; ++k) {
                    int ns = -1;
                    if (a1 == 0) {
                        ns = k;
                    } else if (a2 == 0) {
                        if (k <= a1) {
                            ns = k;
                        } else {
                            ns = a1 + k * b;
                        }
                    } else if (a3 == 0) {
                        if (k <= a1) {
                            ns = k + a2 * b;
                        } else if (k <= a2) {
                            ns = a1 + k * b;
                        } else {
                            ns = a1 + a2 * b + k * b * b;
                        }
                    } else {
                        if (k <= a1) {
                            ns = k + a2 * b + a3 * b * b;
                        } else if (k <= a2) {
                            ns = a1 + k * b + a3 * b * b;
                        } else if (k <= a3) {
                            ns = a1 + a2 * b + k * b * b;
                        } else {
                            // invalid
                        }
                    }
                    if (ns != -1) {
                        dp[i][ns] = (dp[i][ns] + dp[i - 1][j]) % mod;
                    }
                }
            }
        }
    }
    ll ans = 0;
    for (int i = 0; i < state; ++i) {
        ans += dp[n][i];
    }
    cout << (ans % mod) << endl;
    return 0;
};