Parenthesis Checker.cpp

/*
Parenthesis Checker
===================

Given an expression string x. Examine whether the pairs and the orders of “{“,”}”,”(“,”)”,”[“,”]” are correct in exp.
For example, the function should return 'true' for exp = “[()]{}{[()()]()}” and 'false' for exp = “[(])”.

Example 1:
Input:
{([])}
Output: 
true
Explanation: 
{ ( [ ] ) }. Same colored brackets can form 
balaced pairs, with 0 number of 
unbalanced bracket.

Example 2:
Input: 
()
Output: 
true
Explanation: 
(). Same bracket can form balanced pairs, 
and here only 1 type of bracket is 
present and in balanced way.

Example 3:
Input: 
([]
Output: 
false
Explanation: 
([]. Here square bracket is balanced but 
the small bracket is not balanced and 
Hence , the output will be unbalanced.
Your Task:
This is a function problem. You only need to complete the function ispar() that takes a string as a parameter and returns a boolean value true if brackets are balanced else returns false. The printing is done automatically by the driver code.

Expected Time Complexity: O(|x|)
Expected Auixilliary Space: O(|x|)

Constraints:
1 ≤ |x| ≤ 32000

Note: The drive code prints "balanced" if function return true, otherwise it prints "not balanced".
*/

bool ispar(string x)
{
  stack<char> s;
  for (auto &i : x)
  {
    if (i == '(' || i == '{' || i == '[')
      s.push(i);
    else
    {
      if (!s.size())
        return false;
      if (i == ')' && s.top() == '(')
        s.pop();
      else if (i == ']' && s.top() == '[')
        s.pop();
      else if (i == '}' && s.top() == '{')
        s.pop();
      else
        return false;
    }
  }
  if (s.size())
    return false;
  return true;
}