Bracket sequence

input/code.cpp: In function 'void solve()':
input/code.cpp:30:23: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   30 |     for (int i = 0; i < s.size(); i++)
      |                     ~~^~~~~~~~~~

#include <iostream>
#include <vector>
#include <array>
#include <string>
#include <algorithm>
#include <numeric>
#include <unordered_map>
#include <unordered_set>
#include <queue>
#include <climits>
#include <cmath>
#include <functional>
#include <type_traits>
#include <fstream>
#include <bitset>
 
#define int long long
using namespace std;
 

void solve() {
    string s;
    cin >> s;

    vector<int> start;
    start.reserve(s.size());

    int maxLength = 0;
    int maxIdx = -1;
    for (int i = 0; i < s.size(); i++)
    {
        if (s[i] == '(')
        {
            start.push_back(i);
        }
        else
        {
            if (start.empty())
                continue;
            
            if (start.back() == maxIdx + maxLength + 1)
            {
                maxLength += i - start.back() + 1;
            }
            else if (i - start.back() > maxLength)
            {
                maxLength = i - start.back();
                maxIdx = start.back();
            }

            start.pop_back();

        }
    }


    if (maxIdx == -1)
        cout << -1;
    else
        cout << s.substr(maxIdx, maxLength+1);
}
 
 
signed main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
 
    int t = 1;
 
    //cin >> t;
    //ifstream f("testcase.txt");
    //cin.rdbuf(f.rdbuf());
 
    for (int i = 0; i < t; i++)
        solve();
 
    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: WRONG ANSWER

Test 5

Verdict: ACCEPTED

Test 6

Verdict: WRONG ANSWER

Test 7

Verdict: ACCEPTED

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: ACCEPTED

Test 13

Verdict: WRONG ANSWER

Test 14

Verdict: WRONG ANSWER

Test 15

Verdict: WRONG ANSWER

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: ACCEPTED

Test 23

Verdict: WRONG ANSWER

Test 24

Verdict: WRONG ANSWER

Test 25

Verdict: WRONG ANSWER

Test 26

Verdict: WRONG ANSWER

Test 27

Verdict: ACCEPTED

Test 28

Verdict: ACCEPTED

Test 29

Verdict: ACCEPTED

Test 30

Verdict: ACCEPTED

Test 31

Verdict: WRONG ANSWER

Test 32

Verdict: ACCEPTED

Test 33

Verdict: ACCEPTED

Test 34

Verdict: WRONG ANSWER

Test 35

Verdict: WRONG ANSWER

Test 36

Verdict: ACCEPTED

Test 37

Verdict: ACCEPTED

Test 38

Verdict: ACCEPTED

Test 39

Verdict: ACCEPTED

Test 40

Verdict: ACCEPTED

Test 41

Verdict: WRONG ANSWER

Test 42

Verdict: ACCEPTED

Test 43

Verdict: WRONG ANSWER

Test 44

Verdict: WRONG ANSWER

Test 45

Verdict: WRONG ANSWER

Test 46

Verdict: ACCEPTED

Test 47

Verdict: ACCEPTED

Test 48

Verdict: WRONG ANSWER

Test 49

Verdict: ACCEPTED

Test 50

Verdict: ACCEPTED

Test 51

Verdict: ACCEPTED

Test 52

Verdict: ACCEPTED

Test 53

Verdict: WRONG ANSWER

Test 54

Verdict: WRONG ANSWER

Test 55

Verdict: ACCEPTED

Test 56

Verdict: ACCEPTED

Test 57

Verdict: ACCEPTED

Test 58

Verdict: ACCEPTED

Test 59

Verdict: ACCEPTED

Test 60

Verdict: ACCEPTED

Test 61

Verdict: ACCEPTED

Test 62

Verdict: ACCEPTED

Test 63

Verdict: WRONG ANSWER

Test 64

Verdict: WRONG ANSWER

Test 65

Verdict: WRONG ANSWER