784. Letter Case Permutation

Medium

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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.