BOJ)9012 괄호

https://www.acmicpc.net/problem/9012

#include <iostream>
#include <stack>
#include <cstring>
using namespace std;
 
stack <char> s_left;
 
int main()
{
    int t;
    cin >> t;
    char s[51];
    while (t--) {
        bool b = false;
 
        cin >> s;
        for (int i = 0; i < strlen(s); i++) {
            if (s[i] == '(') {
                s_left.push(s[i]);
            }
            else {
                if (s_left.empty()) { b = false; break; }
                else {
                    s_left.pop();
                    b = true;
                }
            }
        }
        if (!s_left.empty()) b = false;
        cout << ( b ? "YES" : "NO") << "\n";
        while (!s_left.empty()) s_left.pop();
    }
    return 0;
}