leetcode (9) - the telephone number of letter combinations

Given a string contains only numeric characters 2-9, it can return all letter combinations indicated.

Given digital map to letters as follows (the same telephone key). Note 1 does not correspond to any alphabet.

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

Nothing to say, it is time to test the other hand cheap play a few numbers, the computer can not move the card

class Solution:
    def letterCombinations(self, digits: str):
        if len(digits)==0:
            return []
        maps = {
            2:['a','b','c'],
            3:['d','e','f'],
            4:['g','h','i'],
            5:['j','k','l'],
            6:['m','n','o'],
            7:['p','q','r','s'],
            8:['t','u','v'],
            9:['w','x','y','z']
        }
        lists = maps[int(digits[0])]
        for each in digits[1:]:
            new_lists = []
            for s in lists:
                for c in maps[int(each)]:
                    new_lists.append(s+c)
            lists= new_lists
           
        return lists
#s = Solution()