Generate Keypad Letter Permutations | Dataford Interview Questions

Given a telephone keypad, write a program that generates all possible permutations of letter strings.

Implement the function using the standard mapping from digits 2 through 9 to telephone keypad letters. Return combinations in keypad order, and return an empty list when the input is empty.

Input: a string digits. Output: a list of strings, with one character selected for each input digit.

Constraints

digits is a string containing only characters from "2" through "9"
0 <= len(digits) <= 4
Return combinations in the order produced by the keypad mapping
The output contains one string for every possible letter selection

Function Signature

def letter_combinations(digits):

Your question is Generate Keypad Letter Permutations. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem