Kortit II

input/code.cpp: In function 'int main()':
input/code.cpp:93:38: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   93 |             if (current_draws.size() != n - a - b) continue;
      |                 ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~
input/code.cpp:115:66: warning: comparison of integer expressions of different signedness: 'size_t' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
  115 |                     if (A > a || B > b || (A <= a && B <= b && j == apb - 1)) {
      |                                                                ~~^~~~~~~~~~

#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <iterator>
#include <iomanip>
#include <list>
#include <numeric>
 
using namespace std;
 
 
int mod_factorial(int n) {
    long long result = 1;
    for (int i = 2; i <= n; ++i) {
        result = (result * i) % 1000000007;
    }
    return result;
}
long long factorial(int n) {
    long long result = 1;
    for (int i = 2; i <= n; ++i) {
        result *= i;
    }
    return result;
}
 
long long nCr(int n, int k) {
    long long result = mod_factorial(n)/mod_factorial(n-k);
    return result;
}
 
vector<int> ith_permutation(const vector<int>& l, int i) {
    int n = l.size();
    vector<long long> fact(n, 1);
    vector<int> perm(n, 0);
 
    for (int k = 1; k < n; ++k) {
        fact[k] = fact[k - 1] * k;
    }
 
    for (int k = 0; k < n; ++k) {
        perm[k] = i / fact[n - 1 - k];
        i = i % fact[n - 1 - k];
    }
 
    for (int k = n - 1; k > 0; --k) {
        for (int j = k - 1; j >= 0; --j) {
            if (perm[j] <= perm[k]) {
                perm[k]++;
            }
        }
    }
 
    vector<int> result;
    for (int x : perm) {
        result.push_back(l[x]);
    }
    return result;
}
 
int main() {
    int t;
    cin >> t;
 
    vector<vector<int>> vals(t);
    for (int test = 0; test < t; ++test) {
        int n, a, b;
        cin >> n >> a >> b;
        vals[test] = {n, a, b};
    }
 
    for (const auto& test : vals) {
        int n = test[0], a = test[1], b = test[2];
        if (a + b == 1 || a + b > n) {
            cout << 0 << endl;
            continue;
        }
        long long possibles = 0;
        int apb = a + b;
        long long _fac = factorial(apb) - 1;
 
        vector<int> draws(n);
        iota(draws.begin(), draws.end(), 0);
 
        for (int draw = 0; draw < (1 << (n - a - b)); ++draw) {
            vector<int> current_draws;
            for (int j = 0; j < n; ++j) {
                if (draw & (1 << j)) {
                    current_draws.push_back(j);
                }
            }
            if (current_draws.size() != n - a - b) continue;
 
            vector<int> pairs(n);
            iota(pairs.begin(), pairs.end(), 0);
            for (int draw : current_draws) {
                pairs.erase(remove(pairs.begin(), pairs.end(), draw), pairs.end());
            }
            
 
            long long i = _fac;
            while (i >= 0) {
                vector<int> perm = ith_permutation(pairs, i);
                int A = 0, B = 0;
 
                for (size_t j = 0; j < pairs.size(); ++j) {
                    int pair1 = pairs[j], pair2 = perm[j];
                    if (pair2 < pair1) {
                        A++;
                    } else if (pair2 > pair1) {
                        B++;
                    }
 
                    if (A > a || B > b || (A <= a && B <= b && j == apb - 1)) {
                        i -= factorial(apb - j - 1);
                        break;
                    }
                }
 
                if (A == a && B == b) {
                    possibles++;
                }
            }
        }
 
        possibles = (((possibles * mod_factorial(n)) % 1000000007) * nCr(n, n-apb));
        cout << possibles << "\n";
    }
 
    return 0;
}

Test 1

Group: 1, 2, 3, 4, 5

Verdict: TIME LIMIT EXCEEDED

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