Submission #810955

#	Time	Username	Problem	Language	Result	Execution time	Memory
810955		vjudge1	Tents (JOI18_tents)	C++17	100 / 100	77 ms	70876 KiB

tents

#include <bits/stdc++.h>
using namespace std;

int32_t main() {
        ios_base::sync_with_stdio(0);
        cin.tie(0);
        int n, m;
        cin >> n >> m;
        const int MOD = 1e9 + 7;
        vector<vector<int64_t>> f(n + 1, vector<int64_t>(m + 1, 1));
        for (int i = 1; i <= n; i++) {
                for (int j = 0; j <= m; j++) {
                        f[i][j] = f[i - 1][j];
                        if (j > 0) (f[i][j] += f[i - 1][j - 1] * j * 4) %= MOD;
                        if (i > 1) (f[i][j] += f[i - 2][j - 1] * (i - 1) * j) %= MOD;
                        if (j > 1) (f[i][j] += f[i - 1][j - 2] * j * (j - 1) / 2) %= MOD;
                }
        }
        cout << (f[n][m] + MOD - 1) % MOD;
}

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