← Scale.ai Interview Insights

Scale.ai·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
Jun 2026

Summary

Scale.ai debugging round for a Software Engineer role, this one focused on fixing a sort bug in a project assignment feature. Pretty targeted exercise, just one bug to track down and fix, but the details mattered.

Questions Asked (1)

Q1

You're given code where projects are being sorted in ascending priority order, but the system should process higher-priority projects first. Find the sort logic and fix it so the ordering is correct.

Root Cause AnalysisAlgorithms & Data Structures
Author's notes

The fix itself is small, like a one-line comparator flip, but I spent more time than I should've re-reading the surrounding code to make sure I wasn't missing some intentional design choice.

Create a free account to read the full note

AI HintsAI Generated

Suggested Approach

First, locate the sorting logic and identify the comparator or key function used. Then, analyze the current ordering direction and modify it to reverse the priority order, ensuring higher priority values come first. Finally, verify the fix with test cases covering edge cases like equal priorities and empty lists.

Pro tip: When reversing a sort, consider whether the priority values are numeric or categorical; for numeric, simply negate the comparator or use reverse=True, but for categorical, you may need to define a custom order. Also, check if the sort is stable and whether reversing affects secondary criteria.

1. Locate the sorting logic

Search the codebase for sorting functions, comparators, or key functions related to projects and priority. Identify the exact line or block responsible for ordering.

2. Understand the current ordering

Determine how the current sort works: is it ascending by priority value? What data type is priority? Are there any secondary sort keys?

3. Reverse the ordering

Modify the sort to process higher priorities first. For numeric priorities, negate the comparator or use a descending sort. For custom orders, adjust the key function accordingly.

4. Test the fix

Run existing tests and add new ones to verify that projects are now ordered from highest to lowest priority. Include edge cases such as equal priorities and empty input.

5. Consider side effects

Check if the sort is used elsewhere and whether reversing it impacts other functionality. Ensure the change is localized and doesn't break dependent code.

Key Points to Mention

  • Identify the comparator or key function used for sorting.
  • Understand the priority data type (e.g., numeric, enum) to choose the correct reversal method.
  • Use descending sort (e.g., reverse=True in Python, or negate comparator).
  • Maintain stability if secondary sort criteria exist.
  • Test with edge cases: equal priorities, empty list, single element.
  • Consider performance implications if sorting large datasets.

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