Letter Combinations of a Phone Number
Explore how to generate all possible letter combinations for a given string of digits from 2 to 9 using JavaScript. Understand the mapping of digits to letters on a phone keypad and practice implementing an efficient algorithm to solve this classic coding interview problem.
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Statement
Given a string containing digits from 2 to 9 inclusive, with the possibility of each digit appearing multiple times, return all possible letter combinations that the number could represent. Return the answer in any order.
The illustration below shows the mapping of digits to letters in a telephone dial pad.
Note: The number on the telephone dial pad does not correspond to any letter, so the input string only contains digits from to .
Constraints:
-
digits.length -
digits[i]is a digit in the range
Examples
Understand the problem
Let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:
Letter Combinations of a Phone Number
What should be the output if the following digits are given as input?
Digits = 29
[aw, ax, ay, az]
[bw, bx, by, bz]
[aw, ax, ay, az, bw, bx, by, bz, cw, cx, cy, cz]
[cw, cx, cy, cz]
Figure it out!
We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.
Try it yourself
Implement your solution in the following coding playground:
export function letterCombinations(digits){// Replace this placeholder return statement with your codereturn []}