Check for balanced with only one type of brackets

Given a string str of length N, consisting of '(' and ')' only, the task is to check whether it is balanced or not.
Examples:

Input: str = "((()))()()" 
Output: Balanced

Input: str = "())((())" 
Output: Not Balanced 

Approach 1:

• Declare a Flag variable which denotes expression is balanced or not.
• Initialise Flag variable with true and Count variable with 0.
• Traverse through the given expression
• If we encounter an opening parentheses (, increase count by 1
• If we encounter a closing parentheses ), decrease count by 1
• If Count becomes negative at any point, then expression is said to be not balanced, 
  so mark Flag as false and break from loop.
• After traversing the expression, if Count is not equal to 0, 
  it means the expression is not balanced so mark Flag as false.
• Finally, if Flag is true, expression is balanced else not balanced.

Below is the implementation of the above approach:

Balanced 
Not Balanced 

Time complexity: O(N) 
Auxiliary Space: O(1)

Approach 2: Using Stack

• Declare stack.
• Iterate string using for loop charAt() method.
• If it is an opening bracket then push it to stack
• else if it is closing bracket and stack is empty then return 0.
• else continue iterating till the end of the string.
• at every step check top element of stack using peek() and pop() element accordingly
• end loop

Valid

Time complexity: O(N) 
Auxiliary Space: O(1)