[Solved] Given a string s, you can transform every letter individually to be lowercase or uppercase to create another string. Return a list of all possible strings we could create. Return the output in any order.

Question

Given a string s, you can transform every letter individually to be lowercase or uppercase to create another string.

Return a list of all possible strings we could create. Return the output in any order.

Example 1:

Input: s = "a1b2"
Output: ["a1b2","a1B2","A1b2","A1B2"]

Example 2:

Input: s = "3z4"
Output: ["3z4","3Z4"]

Constraints:

• 1 <= s.length <= 12
• s consists of lowercase English letters, uppercase English letters, and digits.

Python Solution

class Solution:
    def letterCasePermutation(self, s: str) -> List[str]:
        r=['']

        for ch in s:
            if ch.isalpha():
                r = [i+j for i in r for j in [ch.upper(),ch.lower()]]
            else:
                r = [i+ch for i in r]

        return(r)