Letter Case Permutation

Medium

https://leetcode.com/problems/letter-case-permutation/

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

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

Example 1:

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

Example 2:

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

Example 3:

Input: s = "12345"
Output: ["12345"]

Example 4:

Input: s = "0"
Output: ["0"]

Constraints:

• s will be a string with length between 1 and 12.
• s will consist only of letters or digits.