MyCodeSchool Problem #44

BalancedParentheses.cc

#include <iostream>
#include <string>
#include <vector>

using namespace std;

class BalancedParentheses {
  public:
  int checkBalance(string);
};

int BalancedParentheses::checkBalance(string input) {
  int counter = 0;
  vector<char> vec;

  for(string::size_type i = 0; i < input.size(); ++i) {
    if(i == 0 && input[i] == ')')
      return -1;
    if(i == 0 && input[i] == '}')
      return -1;

    if(input[i] == '(' || input[i] == '{') {
      vec.push_back(input[i]);
      ++counter;
    } else if(input[i] == ')' || input[i] == '}') {
      if(!vec.empty())
        switch(input[i]) {
          case ')':
            if(vec[vec.size()-1] == '(') {
              vec.pop_back();
              --counter;
            }
            break;
          case '}':
           if(vec[vec.size()-1] == '{') {
              vec.pop_back();
              --counter;
            }
            break;
        }
      }
    }
  return counter;
}

int main() {
  BalancedParentheses obj;
  int cases;
  string s;

  cin >> cases;

  for(int i = 0; i < cases; ++i) {
    cin >> s;
    cout << (obj.checkBalance(s) == 0 ? "YES" : "NO") << endl;
  }
}