#678

Valid Parenthesis String

medium· Greedyruns: 0

Given a string s containing only three types of characters: '(', ')' and '*', return true if s is valid. Rules: any left parenthesis must have a matching right; any right must have a matching left; left must come before its corresponding right; '*' can be treated as a single right, a single left, or an empty string.

wpm 0acc 100%time 0:000 / 438

class Solution:
    def checkValidString(self, s: str) -> bool:
        low = high = 0
        for c in s:
            if c == "(":
                low += 1
                high += 1
            elif c == ")":
                low -= 1
                high -= 1
            else:
                low -= 1
                high += 1
            if high < 0:
                return False
            low = max(low, 0)
        return low == 0

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