UVa 673 - Parentheses Balance

uva-673.cpp

#include <cstdio>
#include <stack>
#include <iostream>
#include <string>

using namespace std;

int main(void) {
  int n;
  string s;
  while(cin >> n) {
    getchar();
    while(n--) {
      getline(cin, s);
      stack<char> stk;
      bool correct = true;
      for(int i=0; i<s.length() && correct; i++) {
        switch(s[i]) {
          case '[':
          case '(':
            stk.push(s[i]);
            break;
          case ']':
            if(!stk.empty() && stk.top() == '[') {
              stk.pop();
              break;
            } else {
              correct = false;
              break;
            }
          case ')':
            if(!stk.empty() && stk.top() == '(') {
              stk.pop();
              break;
            } else {
              correct = false;
              break;
            }
          default:
            break;
        }
      }
      if(correct && stk.empty()) {
        cout << "Yes" << endl;
      } else {
        cout << "No" << endl;
      }
    }
  }
  return 0;
}