Letter-Combinations-of-a-Phone-Number

Solution of Letter Combinations of a Phone Number

題目 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. Return the answer in any order.

A mapping of digits to letters (just like on the telephone buttons) is given below. Note that 1 does not map to any letters.

ex1:

Input:
digits = "23"

Output:
["ad","ae","af","bd","be","bf","cd","ce","cf"]

ex2:

Input:
digits = "2"

Output:
["a","b","c"]

想法

• 設定一個 phone 字典對應數字與字母的關係
• 設立一個函數 run 進行字母的遍歷，加入字母可能的配對