balance_parenthesis.py

## Balance parenthesis check
#

def checker(s):
    # Check length
    if(len(s) % 2 != 0):
        return False
    
    # set of opening brackets
    opening = set('([{')
    # set of matching pair
    matches = set([ ('(',')'), ('[', ']'), ('{', '}')])

    # stack
    stack = []

    # Check parenthesis
    for paren in s:
        if paren in opening:
            stack.append(paren)
        else:
            if len(stack) == 0:
                return False
            
            last_open = stack.pop()

            if(last_open, paren) not in matches:
                return False

    return len(stack) == 0


# Feed
pa = '[]'
result = checker(pa)
print("{} - {}".format(pa, result))

pa = '[]['
result = checker(pa)
print("{} - {}".format(pa, result))