Check if multiple brackets are balanced.

bracket_balancing.py

def is_balanced(s):
    """
    Check if a string has balanced brackets.
    
    Parameters
    ----------
    
    s: str
        String to be checked.
        
    Returns
    -------
    
    True if the rbackets are balanced. False otherwise 
    """
    if len(s) == 1:
        # Only one char. It can't be balanced
        return False
    else: 
        # Add counters
        count_dic = {'[':0, 
                     '(':0, 
                     '{':0}

        # Bracket reference
        ref_dic = {']':'[',
                   ')':'(',
                   '}':'{'}


        # Store the opening brackets checked
        bracket_list = []

        for char in s:
            if char in count_dic.keys():
                count_dic[char] += 1
                bracket_list.append(char)
            elif char in ref_dic.keys():
                # Decerease count
                count_dic[ref_dic[char]] -= 1

                # Check if it matches the last one
                if ref_dic[char] == bracket_list[-1]:
                    _ = bracket_list.pop()
                else:
                    return False

            # Check if any counter is negative
            for count in count_dic.values():
                if count < 0:
                    return False

        return True
    

assert is_balanced("[()]{a}{[(())]()}")
assert not is_balanced("[(])")
assert not is_balanced("(((]]]")
assert not is_balanced(')')