Merkkijonot

input/code.cpp: In function 'int main()':
input/code.cpp:18:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   18 |         for(int k = 0; k < s.size(); k++){
      |                        ~~^~~~~~~~~~
input/code.cpp:38:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   38 |     for(int i = 1; i <= v.size(); i++){
      |                    ~~^~~~~~~~~~~

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

const ll MOD = 1000000007;

ll dp[501][251][251];

int main() {
    int n; cin >> n;

    vector<pair<int, int>> v;

    int aTotal = 0; int bTotal = 0;
    for(int i = 0; i < n; i++){
        string s; cin >> s;
        int a = 0; int b = 0;
        for(int k = 0; k < s.size(); k++){
            if(s[k] == 'a'){
                a++;
                aTotal++;
            }
            else{
                b++;
                bTotal++;
            }
        }
        v.push_back(make_pair(a, b));
    }

    if(aTotal % 2 != 0 || bTotal % 2 != 0){
        cout << 0;
        return 0;
    }

    
    dp[0][0][0] = 1;
    for(int i = 1; i <= v.size(); i++){
        for(int a = 0; a <= 251; a++){
            for(int b = 0; b <= 251; b++){
                if(a-v[i-1].first < 0 || b-v[i-1].second < 0){
                    dp[i][a][b] = dp[i-1][a][b];
                }
                else{
                    dp[i][a][b] = (dp[i-1][a][b] + dp[i-1][a-v[i-1].first][b-v[i-1].second]) % MOD;
                }
            }
        }
    }

    ll ans = dp[v.size()][aTotal / 2][bTotal / 2];
    cout << ans << "\n";



    /*
    v = 1, 1, 1, 1

    (0, 0) = 1
    (1, 1) = 1
    (1, 0) = 1
    (2, 1) = 2
    (3, 1) = 3
    (4, 1) = 3+


    */
    
}

/*
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*/

Test 1

Group: 1, 2, 3

Verdict: ACCEPTED

Test 2

Group: 1, 2, 3

Verdict: ACCEPTED

Test 3

Group: 1, 2, 3

Verdict: ACCEPTED

Test 4

Group: 1, 2, 3

Verdict: ACCEPTED

Test 5

Group: 2, 3

Verdict: ACCEPTED

Test 6

Group: 2, 3

Verdict: ACCEPTED

Test 7

Group: 2, 3

Verdict: ACCEPTED

Test 8

Group: 2, 3

Verdict: ACCEPTED

Test 9

Group: 3

Verdict: ACCEPTED

Test 10

Group: 3

Verdict: ACCEPTED

Test 11

Group: 3

Verdict: ACCEPTED

Test 12

Group: 3

Verdict: ACCEPTED

Test 13

Group: 3

Verdict: ACCEPTED

Test 14

Group: 3

Verdict: ACCEPTED

Test 15

Group: 2, 3

Verdict: ACCEPTED

Test 16

Group: 3

Verdict: ACCEPTED