20. Valid Parentheses - Leetcode

solution.py

# https://leetcode.com/problems/valid-parentheses/#/description
class Solution(object):
    CLOSED_BRACKET_DICT = {
        ')' : '(',
        '}' : '{',
        ']' : '['
    }
    def isValid(self, s):
        """
        :type s: str
        :rtype: bool
        """
        stack = []
        
        for c in s:
            if c == '(' or c == '{' or c == '[':
                stack.append(c)
            else:
                if c in self.CLOSED_BRACKET_DICT:
                    if stack and stack[-1] == self.CLOSED_BRACKET_DICT[c]:
                        stack.pop()
                        continue
                    else:
                        return False

        if stack:
            return False
        else:
            return True
                

I believe people tend to prefer immediate return rather than an else: return (at least in my workplace they do).
More SO discussion. I tend to agree as verbosity is annoying.

e.g.

        if stack:
            return False
        else:
            return True

Preferable:

        if stack:
            return False
        return True

1 char variables are okay as long as you explain them. But I'd generally shy away from c and s even though it's fairly self explanatory in this context.