Kortit II

input/code.cpp: In function 'll rf(int, int)':
input/code.cpp:29:31: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   29 |         if (A<a && v.size()+1 < i) {
      |                    ~~~~~~~~~~~^~~
input/code.cpp:36:31: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   36 |         if (B<b && v.size()+1 > i) {
      |                    ~~~~~~~~~~~^~~

#include<bits/stdc++.h>
using namespace std;
#define forn(i,n) for(int i=0;i<n;++i)
#define forN(i,k,n) for(int i=k;i<n;++i)
#define pb push_back
#define F first
#define S second
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
#define inf ((int)(1.01e9))
#define mod ((int)(1e9+7))
#define N ((int)(2002))
 
ll n, m, a, b, counter, result, fact[N];
unordered_map<ll,ll> mem;
vector<int> v;
bool used[N];

ll nCr(int n, int r) {
    if (!r) return 1;
    return (fact[n] / (fact[r] * fact[n-r]))%mod;
}

ll rf(int A, int B) {
    if (A==a && B==b) return 1;
    ll counter = 0;
    forN(i,1,n+1) if (!used[i]) {
        if (A<a && v.size()+1 < i) {
            v.pb(i);
            used[i] = true;
            counter += rf(A+1, B);
            used[i] = false;
            v.pop_back();
        }
        if (B<b && v.size()+1 > i) {
            v.pb(i);
            used[i] = true;
            counter += rf(A, B+1);
            used[i] = false;
            v.pop_back();
        } 
        counter %= mod;
    }
    return counter % mod;
}
 
void solve() {
    cin >> m >> a >> b;
    if (m < a + b || ((!b)&&a) || ((!a)&&b)) {
        cout << "0" << endl;
        return;
    }
    if (a > b) swap(a,b);
    n = a + b;
 
    ll hash = n+a*1000LL+b*1000000LL;
    ll comb = nCr(m,m-n);
    comb = comb*comb*fact[m-n]*fact[n];
    
    if (mem.find(hash) != mem.end()) {
        cout << mem[hash]*comb << endl;
        return;
    }

    v.clear();
    counter = rf(0, 0);

    if (!counter) counter=1;
    result = (counter*comb) % mod;
    mem[hash] = counter;
    cout << result << endl;
}
 
int main() {
    cin.tie(0) -> sync_with_stdio(0);
    cout.tie(0);
    fact[0] = fact[1] = 1;
    forN(i,2,N) fact[i] = (i)*fact[i-1];
 
    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: TIME LIMIT EXCEEDED

Test 4

Group: 4, 5

Verdict: TIME LIMIT EXCEEDED

Test 5

Group: 5

Verdict: RUNTIME ERROR

Test 6

Group: 5

Verdict: RUNTIME ERROR