# Letter Combinations of a Phone Number - Coding Interview Problem

Last modified: April 7, 2023

## Problem Description

Given a string `digits`

containing digits from 2-9 inclusive, return all possible letter combinations that the number could represent. The mapping of digits to letters is as follows:

`{ "2": "abc", "3": "def", "4": "ghi", "5": "jkl", "6": "mno", "7": "pqrs", "8": "tuv", "9": "wxyz" }`

Constraints:

`0 <= digits.length <= 4`

`digits[i]`

is a digit from`'2'`

to`'9'`

.

### Example 1

Input: digits = "23"

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

### Example 2

Input: digits = ""

Result: []

### Example 3

Input: digits = "2"

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