Submission #1021211

#	Time	Username	Problem	Language	Result	Execution time	Memory
1021211		aufan	Tents (JOI18_tents)	C++17	100 / 100	161 ms	71052 KiB

tents

#include <bits/stdc++.h>
#define int long long
#define fi first
#define se second

using namespace std;

const int mod = 1e9 + 7;

int32_t main()
{
        ios_base::sync_with_stdio(false);
        cin.tie(NULL);
        
        int n, m;
        cin >> n >> m;

        vector<vector<int>> dp(n + 1, vector<int>(m + 1));
        for (int i = 0; i <= n; i++) dp[i][0] = 1;
        for (int i = 0; i <= m; i++) dp[0][i] = 1;
        for (int i = 1; i <= n; i++) {
                for (int j = 1; j <= m; j++) {
                        dp[i][j] += dp[i - 1][j - 1] * j % mod * 4 % mod;
                        dp[i][j] %= mod;

                        if (i - 2 >= 0) {
                                dp[i][j] += dp[i - 2][j - 1] * (i - 1) % mod * j % mod;
                                dp[i][j] %= mod;
                        }

                        if (j - 2 >= 0) {
                                dp[i][j] += dp[i - 1][j - 2] * (j * (j - 1) / 2 % mod) % mod;
                                dp[i][j] %= mod;
                        }

                        dp[i][j] += dp[i - 1][j];
                        dp[i][j] %= mod;
                }
        }

        dp[n][m] -= 1;
        dp[n][m] += mod;
        dp[n][m] %= mod;

        cout << dp[n][m] << '\n';
        
        return 0;
}

• Subtask 1: 48 / 48
• Subtask 2: 52 / 52