Submission #866559

#	Time	Username	Problem	Language	Result	Execution time	Memory
866559		ArashJafariyan	Tents (JOI18_tents)	C++17	100 / 100	133 ms	36232 KiB

tents

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

const int N = 3e3 + 4, MOD = 1e9 + 7;

int n, m, _dp[N][N];

int dp(int i, int j) {
    if (i < 0 || j < 0)
        return 0;
    else if (!i || !j)
        return 1;
    else
        return _dp[i][j];
}

int c(int k) {
    return k * (k - 1) / 2;
}

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);

    for (int i = 1; i < N; ++i) {
        for (int j = 1; j < N; ++j) {
            _dp[i][j] = dp(i, j - 1);
            _dp[i][j] = (_dp[i][j] + 4ll * i * dp(i - 1, j - 1) % MOD) % MOD;
            _dp[i][j] = (_dp[i][j] + 1ll * c(i) * dp(i - 2, j - 1) % MOD) % MOD;
            _dp[i][j] = (_dp[i][j] + 1ll * i * (j - 1) * dp(i - 1, j - 2) % MOD) % MOD;
        }
    }

    cin >> n >> m;
    cout << (dp(n, m) + MOD - 1) % MOD;

    return 0;
}

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