LeetCode #20

leetcode-20.py

# https://leetcode.com/problems/valid-parentheses/
class Solution:
    def isValid(self, s):
        """
        :type s: str
        :rtype: bool
        """
        stack = []
        for c in s:
            if c == ")" or c == "]" or c == "}":
                if len(stack) <= 0:
                    return False
                else:
                    c2 = stack.pop()
                    if not((c == ")" and c2 == "(") or (c == "]" and c2 == "[") or (c == "}" and c2 == "{")):
                        stack.append(c2)
                        stack.append(c)
            else:
                stack.append(c)
        return len(stack) <= 0

It is a best solution found that very popular and helpful:
https://www.youtube.com/watch?v=-3S5gH2cuYw&ab_channel=EricProgramming