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#!/usr/bin/env python
from typing import List
class Solution:
def letterCombinations(self, digits: str) -> List[str]:
combinations: List[str] = []
if digits is None or len(digits) == 0:
return combinations
def find_combinations(
combinations,
digits,
previous,
index,
letters_numbers_mapping,
):
if index == len(digits):
combinations.append(previous)
return
letters = letters_numbers_mapping[int(digits[index])]
for i in range(0, len(letters)):
find_combinations(
combinations,
digits,
previous + letters[i],
index + 1,
letters_numbers_mapping,
)
letters_numbers_mapping = [
"",
"",
"abc",
"def",
"ghi",
"jkl",
"mno",
"pqrs",
"tuv",
"wxyz",
]
find_combinations(combinations, digits, "", 0, letters_numbers_mapping)
return combinations
def main():
solution = Solution()
print(solution.letterCombinations("23"))
if __name__ == "__main__":
main()
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