Kortit II

#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, facta[N];
unordered_map<ll,ll> mem;
vector<int> v1, v2;
 
ll fact(int n) {
    if (!facta[n])
        facta[n] = (fact(n-1)*n)%mod;
    return facta[n]; 
}

ll nCr(int n, int r) {
    if (!r) return 1;
    return (fact(n) / (fact(r) * fact(n-r)))%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;
    
    if (mem.find(hash) != mem.end()) {
        cout << mem[hash]*(ll)pow(nCr(m, m-n),2)*fact(m-n) << endl;
        return;
    }
    
    v1.clear();
    forn(i,n) v1.pb(i+1);
    v2 = v1;
    counter = 0;
    do {
        do {
            int cA, cB;
            cA = cB = 0;
            forn(i,n) {
                if (v1[i]>v2[i]) cA++; 
                if (v1[i]<v2[i]) cB++;
            }
            if (cA == a && cB == b) counter=(counter+1)%mod;
        } while (next_permutation(v2.begin(), v2.end()));
    } while (next_permutation(v1.begin(), v1.end()));
    if (!counter) counter=1;
    result = (counter*(ll)pow(nCr(m, m-n),2)*fact(m-n)) % mod;
    mem[hash] = counter;
    cout << result << endl;
}
 
int main() {
    cin.tie(0) -> sync_with_stdio(0);
    cout.tie(0);
    facta[0] = facta[1] = 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: TIME LIMIT EXCEEDED

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