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Amazon·Software Engineer·Online Assessment (OA)·Junior

Junior
May 2026

Summary

Amazon SWE online assessment, one coding problem about Morse code translations. Pretty straightforward set theory problem once you see it, but the input format tripped me up a bit.

Questions Asked (1)

Q1

Given a list of words, translate each word into Morse code by mapping each letter to its corresponding Morse sequence and concatenating them. Return the number of distinct Morse translations across all words.

Algorithms & Data Structures
Author's notes

My first instinct was to overcomplicate it.

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AI HintsAI Generated

Suggested Approach

Use a hash map to store the Morse code for each letter, then for each word, translate it by concatenating the Morse codes of its letters. Insert each translation into a hash set to automatically deduplicate, and finally return the size of the set.

Pro tip: Clarify edge cases upfront: empty input list, empty strings, and non-alphabetic characters. Also, mention that the Morse code for each letter is fixed and unique, so the translation is deterministic.

1. Clarify requirements and edge cases

Ask about input constraints: can words be empty? Are there non-letter characters? What is the maximum length? This shows attention to detail.

2. Choose data structures

Use a hash map for letter-to-Morse mapping (constant time lookup) and a hash set to store distinct translations (automatic deduplication).

3. Translate each word

Iterate through each word, and for each character, look up its Morse code and append to a string builder. Handle any invalid characters appropriately.

4. Count distinct translations

Add each translated string to the set. After processing all words, return the set's size.

5. Analyze complexity and optimize

Time complexity is O(N * L) where N is number of words and L is average length. Space complexity is O(N * L) for the set. Mention potential optimizations if needed.

Key Points to Mention

  • Hash map for O(1) Morse code lookup per character
  • Hash set to automatically handle distinct translations
  • Time and space complexity analysis
  • Edge cases: empty list, empty strings, non-alphabetic characters
  • StringBuilder or equivalent for efficient string concatenation
  • Deterministic mapping ensures consistent translations

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.