Submission #1077639

#	Time	Username	Problem	Language	Result	Execution time	Memory
1077639		kchu_z	Tents (JOI18_tents)	C++17	100 / 100	192 ms	67668 KiB

tents

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

long long dp[3001][3001];
bool visited[3001][3001];

long long MOD = 1e9 + 7;

long long f(int n, int m) {
    if (n < 0 || m < 0) return 0;
    if (n == 0 || m == 0) return 1;

    if (visited[n][m]) return dp[n][m];
    visited[n][m] = 1;

    return dp[n][m] = (f(n - 1, m) + 4 * m * f(n - 1, m - 1) + f(n - 1, m - 2) * m * (m - 1) / 2 + f(n - 2, m - 1) * m * (n - 1)) % MOD;
}

int main() {

    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    int n, m;
    cin >> n >> m;

    cout << (f(n, m) - 1 + MOD) % MOD << endl;
    return 0;

}

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