Valid parenthesis string

class Solution(object):
    def checkValidString(self, s):
        leftMin, leftMax = 0, 0
        for i in s:
            if i == "(":
                leftMin += 1
                leftMax += 1
            elif i == ")":
                leftMin -= 1
                leftMax -= 1
            else:
                leftMin -= 1
                leftMax += 1

            if leftMax < 0:
                return False

            if leftMin < 0:
                leftMin = 0

        return leftMin == 0

Valid Parenthesis String

Difficulty: Medium

Given a string s containing only three types of characters: '(', ')' and '*', return true if s is valid.

The following rules define a valid string:

  • Any left parenthesis '(' must have a corresponding right parenthesis ')'.
  • Any right parenthesis ')' must have a corresponding left parenthesis '('.
  • Left parenthesis '(' must go before the corresponding right parenthesis ')'.
  • '*' could be treated as a single right parenthesis ')' or a single left parenthesis '(' or an empty string "".

 

Example 1:

Input: s = "()"
Output: true

Example 2:

Input: s = "(*)"
Output: true

Example 3:

Input: s = "(*))"
Output: true

 

Constraints:

  • 1 <= s.length <= 100
  • s[i] is '(', ')' or '*'.