leetcode/17.py at master · hashiqi-233/leetcode · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
# -*- coding: utf-8 -*-
# @Time    : 2020/9/14 0014 22:08
# @Author  : zhengwei
# @File    : 17.py
# @Software: PyCharm

class Solution:
    def letterCombinations(self, digits):
        if not digits:
            return []
        phone = {'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']}

        def backtrack(conbination, nextdigit):
            if len(nextdigit) == 0:
                res.append(conbination)
            else:
                for letter in phone[nextdigit[0]]:
                    backtrack(conbination + letter, nextdigit[1:])

        res = []
        backtrack('', digits)
        return res

test = Solution()
result = test.letterCombinations('23')