ericpuwang

电话号码的字母组合

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

给定一个仅包含数字2-9的字符串，返回所有它能表示的字母组合。答案可以按 任意顺序 返回。

给出数字到字母的映射如下（与电话按键相同）。注意 1 不对应任何字母。

示例1

输入：digits = "23"
输出：["ad","ae","af","bd","be","bf","cd","ce","cf"]

示例2

输入：digits = "2"
输出：["a","b","c"]

提示

• 1 <= digits.length <= 4
• digits[i]是范围['2', '9']的一个数字

class Solution:
    def letterCombinations(self, digits: str) -> List[str]:
        phonemap = {
            "2": "abc",
            "3": "def",
            "4": "ghi",
            "5": "jkl",
            "6": "mno",
            "7": "qprs",
            "8": "tuv",
            "9": "wxyz"
        }
        # 笛卡尔积
        queue = [""]
        for digit in digits:
            queue = [i+j for i in queue for j in phonemap[digit]]
        return queue