CS50 vanity plates detecting numbers amid letters

Question

I write a code to verify the license plates of cars and there are some conditions to achieve this purpose:

• The first number should not be 0
• It shouldn't have any numbers between letters(AAA12 is ok, but AA2AAA is not.)
• It should start with two letters
• The count of characters must be between 2 - 6 letters
• Only letters and numbers allowed

def is_valid(s):
    s = s.lower()
    if len(s) >= 2 and len(s) <= 6 and s[0] != 0 and s[0:2].isalpha():
        if s.isalpha():
            return True
        elif s.isalnum():
            for sq in s.split():
                for w in sq:
                    if w.isdigit():
                        x = sq.index(w)
                        try:
                            if s[w:].isalpha():
                                return False
                            else:
                                return True
    
                        except:
                            return True

So my code is doing most of these conditions in a right way, but when I enter e.g. HL23P2, I expect to get False but it returns True.

Why does it return False? because I can't have numbers between letters only it is allowed when its like e.g. HEL23.

But how can I detect numbers between letters?

Answer 1

I think this solution without regular expression would be ok:

def is_valid(s):
    meetNumber = False
    if len(s) >= 2 and len(s) <= 6 and s[0:2].isalpha():
        for i in range(2, len(s)):
            if s[i].isnumeric():
                meetNumber = True
            elif meetNumber == True:
                return False
        return True
    else:
        return False

print(is_valid(input()))