Description
Given a string s, transform every letter individually to be lowercase or uppercase. Return all possible permutations.
Examples
Input:
s = "a1b2"Output:
["a1b2","a1B2","A1b2","A1B2"]Explanation:
All case variations.
Input:
s = "C2c"Output:
["C2c","C2C","c2c","c2C"]Explanation:
String contains uppercase and lowercase letters with a digit. Each letter can be toggled between cases: first 'C' can be 'C' or 'c', last 'c' can be 'c' or 'C', giving us 2×2=4 total permutations.
Input:
s = "12E"Output:
["12E","12e"]Explanation:
String starts with digits and ends with one letter. Only the letter 'E' can change case to 'e', so this gives exactly 2 permutations while the digits '12' remain unchanged in all variations.
Constraints
- •
1 ≤ s.length ≤ 12