Kortit II

input/code.cpp:14:19: warning: use of 'auto' in parameter declaration only available with '-std=c++20' or '-fconcepts'
   14 | void print(vector<auto> v) {
      |                   ^~~~
input/code.cpp: In function 'int solve(std::vector<int>, int, int, int)':
input/code.cpp:49:19: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   49 |     if (p2.size() == n) {
      |         ~~~~~~~~~~^~~~

#include <bits/stdc++.h>

#define F0R(n) for (int i=0; i<n; i++)
#define FOR(from, to) for (int i = from; i < to; i++)
#define R0F(n) for (int i = n; i>=0; --i)
#define ROF(from, to) for (int i = from; i >= to; --i)

#define ll long long
#define mod (int) (1e9 + 7)
#define vi vector<int>
#define pii pair<int, int>
using namespace std;

void print(vector<auto> v) {
	for (auto it = v.begin(); it != v.end(); ++it)
		cout << *it << " ";
}

pii score(vi& p2) {
    int sca=0, scb=0, n = p2.size();
    F0R (n) {
        if (p2[i]<i+1)
            ++sca;
        else if (p2[i]>i+1)
            ++scb;
    }

    return {sca, scb};
}

/*
bool valid(vi& p2, int a, int b) {
    int sca=0, scb=0, n = p2.size();
    F0R (n) {
        if (p2[i]<i+1)
            ++sca;
        else if (p2[i]>i+1)
            ++scb;
        if (sca > a || scb > b)
            return false;
    }

    return (sca == a && scb == b);
}*/

int solve(vi p2, int n, int a, int b) {
    auto [sca, scb] = score(p2);

    if (p2.size() == n) {
        if (sca == a && scb == b) {
            // print(p2);
            return 1;
        }
        else
            return 0;
    }

    if (sca > a || scb > b)
        return 0;

    int ans = 0;
    set<int> st;
    for (int x : p2) st.insert(x);
    F0R (n) {
        if (st.count(i+1)) {
            continue;
        }
        p2.push_back(i+1);
        ans += solve(p2, n, a, b);
        p2.erase(--p2.end());
    }
    return ans;
}

vi fact_mod(2001);
void build() {
    fact_mod[0] = 1;
    FOR (1, 2001)
        (fact_mod[i] = fact_mod[i-1]*i) %= mod;

}

int nCr(int n, int k) {
    if (k <= 0) return 1;
    int ans = 1;
    (ans = fact_mod[n]/(fact_mod[k]*fact_mod[n-k]) ) %= mod;
    return ans;
}

void soln() {
    int n, a, b;
    cin >> n >> a >> b;

    ll ans = 0, fact_mod = 1;

    F0R (n) {
        (fact_mod *= i+1) %= mod;
    }

    if ((a==0 && b!=0) || (a!=0 && b==0)) {
        cout << "0\n";
        return;
    }

    int new_n = n-a-b;
    if (new_n < 0) {
        cout << "0\n";
        return;
    }

    ans = solve({}, a+b, a, b) % mod;
    (ans *= nCr(n, n-a-b)) %= mod;
    (ans *= fact_mod) %= mod;
    cout << ans << "\n";
    return;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    build();
    int tc;
    cin >> tc;
    while (tc--) soln();
    return 0;
}

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: TIME LIMIT EXCEEDED

Test 4

Group: 4, 5

Verdict: TIME LIMIT EXCEEDED

Test 5

Group: 5

Verdict: TIME LIMIT EXCEEDED

Test 6

Group: 5

Verdict: TIME LIMIT EXCEEDED