Submission #1301738

#	Time	Username	Problem	Language	Result	Execution time	Memory
1301738		chikien2009	Tents (JOI18_tents)	C++20	100 / 100	151 ms	82944 KiB

tents

#include <bits/stdc++.h>

using namespace std;

void setup()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
}

const long long mod = 1e9 + 7;

int n, m;
long long f[5001][5001];

int main()
{
    setup();

    cin >> n >> m;
    f[0][0] = 1;
    for (int i = 0; i <= n; ++i)
    {
        for (int j = 0; j <= m; ++j)
        {
            if (i == 0 || j == 0)
            {
                f[i][j] = 1;
                continue;
            }
            (f[i][j] = f[i][j - 1] + f[i - 1][j - 1] * i * 4) %= mod;
            if (2 <= j)
            {
                (f[i][j] += f[i - 1][j - 2] * i * (j - 1)) %= mod;
            }
            if (2 <= i)
            {
                (f[i][j] += f[i - 2][j - 1] * i * (i - 1) / 2) %= mod;
            }
        }
    }
    cout << (f[n][m] - 1 + mod) % mod;
    return 0;
}

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