17. Letter Combinations of a Phone Number

最新推荐文章于 2024-01-18 13:57:19 发布

niunc

最新推荐文章于 2024-01-18 13:57:19 发布

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分类专栏： LeetCode

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本文介绍了一个经典的编程问题：给定一个包含2到9的数字字符串，返回所有可能的字母组合。文章提供了一种递归解决方案，并附带了Python代码实现。

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

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.

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.

Recursive solution is shown below.

class Solution(object):
    def letterCombinations(self, digits):
        """
        :type digits: str
        :rtype: List[str]
        """
        dict = {'2': 'abc', '3': 'def', '4': 'ghi', '5': 'jkl', '6': 'mno', '7': 'pqrs', '8': 'tuv', '9': 'wxyz'}
        if len(digits) == 0:
            return []
        if len(digits) == 1:
            return [char for char in dict[digits]]
        else:
            letters = []
            for i in self.letterCombinations(digits[: -1]):
                for j in dict[digits[-1]]:
                    letters.append(i + j)
            return letters