Letter Combinations of a Phone Number - Coding Interview Problem

Last modified: April 7, 2023
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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"]

Test

Results