Letter Case Permutation

Question

Given a string, write an algorithm to generate all possible letter case permutations of the string.

Example 1

Input: "a1b2"

Output: ["a1b2", "a1B2", "A1b2", "A1B2"]

Solution

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all//Letter Case Permutation.py

def letter_case_permutation(s):
    result = []
    for i in range(len(s)):
        if s[i].isalpha():
            result += [s[:i] + l + s[i+1:] for l in [s[i].lower(), s[i].upper()]]
    return result if result else [s]

# test
s = "a1b2"
print(letter_case_permutation(s)) # output: ["a1b2", "a1B2", "A1b2", "A1B2"]

▯

all//Letter Case Permutation.py

def letter_case_permutation(s):
    result = []
    for i in range(len(s)):
        if s[i].isalpha():
            result += [s[:i] + l + s[i+1:] for l in [s[i].lower(), s[i].upper()]]
    return result if result else [s]

# test
s = "a1b2"
print(letter_case_permutation(s)) # output: ["a1b2", "a1B2", "A1b2", "A1B2"]