Kortit II

#include <iostream>
#include <bits/stdc++.h>
typedef long long ll;
using namespace std;



int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int t;
    cin >> t;
    ll mod = 1e9+7;

    vector<ll> fact(2001);
    vector<vector<ll>> binom(2001, vector<ll>(2001));
    vector<vector<ll>> d(2001, vector<ll>(2001)); //derangmentit

    fact[1] = 1;
    for (int i = 2; i<=2000;i++) {
        fact[i] = (fact[i-1]*(i%mod))%mod;
    }
    binom[0][0] = 1;
    for (int i = 1; i<=2000;i++) {
        binom[i][i] = 1;
        binom[i][0] = 1;
        for (int j = 1; j<=i;j++) {
            binom[i][j] = (binom[i-1][j-1]+binom[i-1][j])%mod;
        }
    }

    d[0][0] = 1;
    for (int k = 0; k<=2000;k++) {
        d[1][k] = 0;
    }
    for (int i = 2; i<=2000;i++) {
        for (int j = 1; j<=i;j++) {
            d[i][j] = ((i-1)*d[i-2][j-1]+(i-j)*d[i-1][j-1]+j*d[i-1][j])%mod;
        }
    }
    while (t--) {
        int n, a, b;
        cin >>n>>a>>b;

        int f = n-a-b;
        if (a>=n || b>=n || a+b>n) {
            cout <<"0\n";
            continue;
        }
        if ((a==0&& b!= 0) || (b==0&&a!=0)) {
            cout <<"0\n";
            continue;
        }
        if (a==0&&b==0) {
            cout <<fact[n]<<"\n";
            continue;
        }
        
        cout <<(fact[n] * binom[n][f] * d[a+b][a])%mod<<"\n";
    }
}

Test 1

Subtask: 1, 2, 3, 4, 5

Verdict: ACCEPTED

Test 2

Subtask: 2, 3, 4, 5

Verdict: ACCEPTED

Test 3

Subtask: 3, 4, 5

Verdict: WRONG ANSWER

Test 4

Subtask: 4, 5

Verdict: WRONG ANSWER

Test 5

Subtask: 5

Verdict: WRONG ANSWER

Test 6

Subtask: 5

Verdict: WRONG ANSWER