# 17. Letter Combinations of a Phone Number

[Leetcode](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.