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Meta·Software Engineer·Online Assessment (OA)·Senior

Senior
Apr 2026

Summary

Meta RS OA, nothing too brutal. One coding problem, felt manageable, and the questions seemed pulled from a known reference so if you've done your reading you're probably fine.

Questions Asked (1)

Q1

Given a list of items with ratings and prices, find the index of the item with the highest rating-to-price ratio. On ties, return the smaller index.

Algorithms & Data Structures
Author's notes

The float division route works but you're asking for precision bugs.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the problem constraints and edge cases, then propose a single-pass linear scan that computes the rating-to-price ratio for each item while tracking the maximum ratio and its index. Emphasize that ties are handled by only updating when a strictly greater ratio is found, ensuring the smaller index is returned.

Pro tip: Mention that using floating-point division can introduce precision issues; instead, compare ratios using cross-multiplication (rating1 * price2 vs rating2 * price1) to avoid floating-point errors, especially when dealing with large numbers or when exact tie-breaking is critical.

1. Clarify Requirements and Edge Cases

Ask about input size, data types (e.g., integers vs floats), possibility of zero or negative prices, and whether the list can be empty. Confirm that ties should return the smaller index.

2. Choose the Right Data Structure and Algorithm

Select a simple linear scan (O(n) time, O(1) space) since we only need to track the best ratio and its index. Avoid sorting or extra data structures unless necessary.

3. Handle Ratio Comparison Carefully

Decide whether to use floating-point division or cross-multiplication to compare ratios. Cross-multiplication avoids precision issues and is exact for integer inputs.

4. Implement the Scan with Tie-Breaking

Initialize best index to 0 and best ratio to the first item's ratio. Iterate from index 1 to n-1, updating only when the current ratio is strictly greater than the best ratio, ensuring ties keep the smaller index.

5. Test and Validate

Walk through edge cases: empty list, single item, all equal ratios, negative prices, and large numbers. Verify that the tie-breaking rule works as expected.

Key Points to Mention

  • Time and space complexity: O(n) time, O(1) space.
  • Tie-breaking: only update when ratio is strictly greater to keep the smaller index.
  • Floating-point precision: prefer cross-multiplication over division for exact comparisons.
  • Edge cases: empty list, single item, zero or negative prices, all equal ratios.
  • Input validation: ensure prices are non-zero to avoid division by zero.
  • Scalability: the linear scan handles large inputs efficiently without extra memory.

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