[Leetcode]2124. Check if All A's Appears Before All B's

📄 Description

Example 1:

Input: s = "aaabbb"
Output: true
Explanation:
The 'a's are at indices 0, 1, and 2, while the 'b's are at indices 3, 4, and 5.
Hence, every 'a' appears before every 'b' and we return true.

Example 2:

Input: s = "abab"
Output: false
Explanation:
There is an 'a' at index 2 and a 'b' at index 1.
Hence, not every 'a' appears before every 'b' and we return false.

Example 3:

Input: s = "bbb"
Output: true
Explanation:
There are no 'a's, hence, every 'a' appears before every 'b' and we return true.

Constraints:

💻 My Submission

class Solution:
    def checkString(self, s: str) -> bool:
        if 'a' and 'b' in s:
            start_b=s.index('b')
            if 'a' in s[start_b:]:
                return False
        return True

💭 Better Solution(1)

class Solution:
    def checkString(self, s: str) -> bool:
        return "ba" not in s

💭 Better Solution(2)

class Solution:
    checkString = re.compile('a*b*').fullmatch

💡 What I learned