[LeetCode]#2124. Check if All A’s Appears Before All B’s

Environment: Python 3.8

Key technique: if

Given a string s consisting of only the characters 'a' and 'b', return true if every 'a' appears before every 'b' in the string. Otherwise, return false.

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.

Analysis:

1. check pattern “ba” is matched with s.
2. If yes, return False. Else, return True.

Solution:

class Solution:
    def checkString(self, s):
        if "ba" in s:
            return False
        else:
            return True

Submissions:

Reference:

https://leetcode.com/problems/check-if-all-as-appears-before-all-bs/discuss/1689073/Python-One-Liner