LeetCode: 17. Letter Combinations of a Phone Number

Problem: 17. Letter Combinations of a Phone Number

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

Difficulty: Medium

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.

Example:

Input: “23”
Output: [“ad”, “ae”, “af”, “bd”, “be”, “bf”, “cd”, “ce”, “cf”].

Solution: 

Language: Swift

Runtime: 8ms
Memory: 20.0MB