@@ -0,0 +1,470 @@
+import itertools%0A%0Aphone_digit_to_letters = %7B%0A    '2': 'abc',%0A    '3': 'def',%0A    '4': 'ghi',%0A    '5': 'jkl',%0A    '6': 'mno',%0A    '7': 'pqrs',%0A    '8': 'tuv',%0A    '9': 'wxyz',%0A%7D%0A%0Aclass Solution:%0A    def letterCombinations(self, digits: str) -%3E List%5Bstr%5D:%0A        if len(digits) == 0:%0A            return %5B%5D%0A        letter_lists = itertools.product(*%5Bphone_digit_to_letters%5Bdigit%5D for digit in digits%5D)%0A        return %5B''.join(letter_list) for letter_list in letter_lists%5D%0A

17. Letter Combinations of a Phone Number