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

IntermediatePrefer not to say
May 2026

Summary

Scale.ai coding round, one part, no dependency stuff to worry about. Pretty clean problem if you know your data structures.

Questions Asked (1)

Q1

Design and implement two functions: one that accepts a list of (taskId, deadline) pairs and adds them to a task queue, and another that processes and returns the task with the smallest deadline.

Algorithms & Data Structures
Author's notes

Heap was the obvious move here and I went straight for it.

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AI HintsAI Generated

Suggested Approach

Clarify requirements and edge cases, then choose a min-heap (priority queue) keyed by deadline for O(log n) insertion and O(log n) extraction. Implement the two functions with clean interfaces, and analyze time/space complexity.

Pro tip: Mention that if deadlines are small integers, a bucket queue can give O(1) operations, showing you consider trade-offs beyond the textbook heap solution.

1. Clarify requirements

Ask about input size, whether deadlines are unique, expected operation frequency, and if the queue must be thread-safe.

2. Choose data structure

Select a min-heap (priority queue) for O(log n) insert and extract-min, or a bucket queue for O(1) if deadlines are bounded integers.

3. Design interfaces

Define function signatures: addTasks(tasks) and processNextTask() returning the task with smallest deadline, handling empty queue.

4. Implement and test

Code the heap operations, write unit tests for edge cases (empty input, duplicate deadlines, single task), and verify correctness.

5. Analyze complexity

State time and space complexity for each operation and discuss potential optimizations or alternative structures.

Key Points to Mention

  • Use a min-heap (priority queue) keyed by deadline for efficient extraction of the smallest deadline.
  • Time complexity: O(log n) for insertion and O(log n) for extraction; space O(n).
  • Handle edge cases: empty queue, duplicate deadlines, null inputs, and large input sizes.
  • Consider thread-safety if the queue is accessed concurrently.
  • Alternative: bucket queue for O(1) operations if deadlines are small integers.
  • Tie-breaking rule for equal deadlines (e.g., FIFO or taskId order).

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