【LeetCode回溯】17. 电话号码的字母组合

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

题目

题解

Python算法

class Solution:
    def letterCombinations(self, digits: str) -> List[str]:
        if not digits:
            return list()
        phoneMap = {
            "2": "abc",
            "3": "def",
            "4": "ghi",
            "5": "jkl",
            "6": "mno",
            "7": "pqrs",
            "8": "tuv",
            "9": "wxyz",}
        
        dig_len = len(digits)
        conbinations = []
        conbination = list()
        def backtrack(ind):
            if ind == dig_len:
                conbinations.append("".join(conbination))
            else:
                for letter in phoneMap[digits[ind]]:
                    conbination.append(letter)
                    backtrack(ind + 1)
                    conbination.pop()

        backtrack(0)
        return conbinations