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Letter Combinations of a Phone Number [C-Solution required]

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#410 opened on Oct 2, 2021

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Description

Given a string containing digits from 2-9 inclusive, return all possible letter combinations that the number could represent. Return the answer in any order.

A mapping of digit to letters (just like on the telephone buttons) is given below. Note that 1 does not map to any letters.

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Example 1:

Input: digits = "23"
Output: ["ad","ae","af","bd","be","bf","cd","ce","cf"]

Example 2:

Input: digits = ""
Output: []

Example 3:

Input: digits = "2"
Output: ["a","b","c"]

Constraints:

  • 0 <= digits.length <= 4
  • digits[i] is a digit in the range ['2', '9'].

Reference: https://leetcode.com/problems/letter-combinations-of-a-phone-number/

Contributor guide

Research direction
Study the backtracking algorithm for letter combinations and implement it in C. Ensure proper memory allocation and string handling.
Tech stack
c
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None
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Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
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1-3 hours
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Active
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Clear
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CGit
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75