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Problem 162

Letter Combinations of a Phone Number

MediumBacktracking

Map digits 2-9 to letters like a phone keypad. Return every combination digits could produce, in lexicographic order. Return [] if digits is empty.

Examples

Example 1

Input: digits = "23"

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

Constraints

0 ≤ digits.length ≤ 4digits[i] is in ['2'..'9']

Target ComplexityNot required

exponential Time · O(depth) Space

Companies (6)

AmazonGoogleMetaMicrosoftAppleBloomberg

Node 22.08.0

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Test casesRun to compare output

Inputdigits = "23"

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

Output—