[17] Letter Combinations of a Phone Number

https://leetcode.com/problems/letter-combinations-of-a-phone-number/description/

• algorithms
• Medium (39.04%)
• Source Code: 17.letter-combinations-of-a-phone-number.py
• Total Accepted: 371.7K
• Total Submissions: 904.6K
• Testcase Example: '"23"'

Given a string containing digits from 2-9 inclusive, return all possible letter combinations that the number could represent.

A mapping of digit to letters (just like on the telephone buttons) is given below. Note that 1 does not map to any letters.

Example:

Input: "23" Output: ["ad", "ae", "af", "bd", "be", "bf", "cd", "ce", "cf"].

Note:

Although the above answer is in lexicographical order, your answer could be in any order you want.

class Solution(object):
    def letterCombinations(self, digits):
        """
        :type digits: str
        :rtype: List[str]
        """