← Amazon Interview Insights

Amazon·Software Engineer·Technical Phone Screen·Intermediate

IntermediatePrefer not to say
Apr 2026

Summary

Amazon SWE coding round, one question, pretty standard frequency-counting problem but the tie-breaking follow-up tripped me up a bit.

Questions Asked (1)

Q1

Given a list of integers or strings, count how often each distinct value appears and return the elements sorted by frequency from highest to lowest. How do you handle ties?

Algorithms & Data Structures
Author's notes

Got the core solution pretty fast.

Create a free account to read the full note

AI HintsAI Generated

Suggested Approach

Start by clarifying the problem constraints and tie-breaking rules, then propose a solution using a hash map to count frequencies and a sort with a custom comparator. Discuss time and space complexity, and consider edge cases like empty input or all unique elements.

Pro tip: At Amazon, interviewers value candidates who proactively discuss trade-offs and scalability. Mention that for large datasets, a bucket sort approach can achieve O(n) time, and always confirm tie-breaking behavior with the interviewer.

1. Clarify requirements

Ask about input size, data types, and how ties should be broken (e.g., by original order, lexicographically, or any order). Confirm if the output should be a list of elements or pairs.

2. Choose data structures

Use a hash map to count frequencies in O(n) time. For sorting, consider using a list of (element, frequency) pairs and sort with a custom comparator.

3. Handle ties

Define a deterministic tie-breaking rule, such as sorting tied elements by their natural order (for strings, lexicographically; for integers, numerically) or by first occurrence.

4. Analyze complexity

State that the hash map approach takes O(n) time and O(n) space, and sorting takes O(k log k) where k is the number of distinct elements. Mention that bucket sort can achieve O(n) if frequencies are bounded.

5. Test with edge cases

Walk through examples like empty input, single element, all elements same, and ties. Verify that the tie-breaking rule is applied consistently.

Key Points to Mention

  • Hash map for frequency counting
  • Sorting with custom comparator
  • Tie-breaking strategy (e.g., lexicographical or by first occurrence)
  • Time and space complexity analysis
  • Bucket sort for O(n) time when applicable
  • Edge cases: empty input, all unique, all same

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