Letter Combinations of a Phone Number

 1from itertools import product 
 2class Solution:
 3    def get_letters(self, x):
 4        if x == 2:
 5            return list("abc")
 6        elif x == 3:
 7            return list("def")
 8        elif x == 4:
 9            return list("ghi")
10        elif x == 5:
11            return list("jkl")
12        elif x == 6:
13            return list("mno")
14        elif x == 7:
15            return list("pqrs")
16        elif x == 8:
17            return list("tuv")
18        elif x == 9:
19            return list("wxyz")
20
21    def letterCombinations(self, digits):
22        """
23        :type digits: str
24        :rtype: List[str]
25        """
26        if digits == "":
27            return []
28        numbers = list(digits)
29        all_letters = []
30        ans = []
31        for num in numbers:
32            temp = self.get_letters(int(num))
33            all_letters.append(temp)
34        combo = list(product(*all_letters))
35        for comb in combo:
36            ans.append(''.join(comb))
37        return ans