August - Day 3 - Valid Palindrome

Solution.py

class Solution:
  def isPalindrome(self, s: str) -> bool:
    def isValid(c: int) -> bool:
      if (c >= ord('0') and c <= ord('9')) or \
         (c >= ord('A') and c <= ord('Z')) or \
         (c >= ord('a') and c <= ord('z')):
        return True
      return False
    
    def sameChar(i: int, j: int) -> bool:
      if s[i] == s[j] or \
         (ord(s[i]) > ord('9') and \
          ord(s[j]) > ord('9') and \
          abs(ord(s[j]) - ord(s[i])) == 32):
        return True
      return False
    
    i = 0
    j = len(s) - 1
    
    while i < j:
      while i < len(s) and not isValid(ord(s[i])):
        i += 1
        
      while j >= 0 and not isValid(ord(s[j])):
        j -= 1
        
      if i > j:
        return True
      
      if not sameChar(i, j):
        return False
      
      i += 1
      j -= 1
    
    return True