Kortit II

#include <bits/stdc++.h>
using namespace std;
#define all(x) x.begin(),x.end()
using ll = long long;
 
const int N = 2000, M = 1e9+7;
ll dp[N+1][N+1];
 
void solve() {
 
    int n, a, b;
    cin >> n >> a >> b;
 
    int p = a+b;
    int t = n-p;
 
    if (p > n) {
        cout << "0\n";
        return;
    }
 
    ll ans = dp[a][b];
    for (int i = p+1; i <= n; i++) ans = (ans * i) % M;
    for (int i = t+1; i <= n; i++) ans = (ans * i) % M;
    cout << ans % M << "\n";
 
}
 
int main() {
    ios_base::sync_with_stdio(0); cin.tie(0);
 
    dp[0][0] = 1;
    for (ll i = 1; i <= N; i++) {
        for (ll j = 1; j <= N; j++) {
            if (i == 1 || j == 1) dp[i][j] = 1;
            else {
                dp[i][j] = (i * dp[i][j-1]) + (j * dp[i-1][j]) + ((i+j-1) * dp[i-1][j-1]);
                dp[i][j] %= M;
            }
        }
    }
 
    int t;
    cin >> t;
    while (t--) solve();
    
}

Test 1

Group: 1, 2, 3, 4, 5

Verdict: ACCEPTED

Test 2

Group: 2, 3, 4, 5

Verdict: ACCEPTED

Test 3

Group: 3, 4, 5

Verdict: ACCEPTED

Test 4

Group: 4, 5

Verdict: ACCEPTED

Test 5

Group: 5

Verdict: ACCEPTED

Test 6

Group: 5

Verdict: ACCEPTED