← Scale.ai Interview Insights

Scale.ai·Machine Learning Engineer·Technical Phone Screen·Intermediate

IntermediatePrefer not to say
Apr 2026

Summary

Scale.ai MLE interview, looks like just one coding question the whole round. Heap problem, went fine.

Questions Asked (1)

Q1

Implement a task scheduler given a list of tasks, each with an id (string) and a deadline (integer). Schedule them appropriately.

Algorithms & Data Structures
Author's notes

Pretty standard heap question once you see what they're asking.

Create a free account to read the full note

AI HintsAI Generated

Suggested Approach

Clarify the scheduling objective (e.g., maximize number of tasks completed, minimize lateness) and constraints (single machine, preemption). Then model it as a classic scheduling problem: sort tasks by deadline and use a greedy algorithm with a min-heap to select tasks, or use dynamic programming for weighted variants. Discuss time/space complexity and potential optimizations.

Pro tip: Always state your assumptions and ask clarifying questions before diving into code; interviewers value candidates who identify ambiguities and edge cases (e.g., tasks with equal deadlines, zero or negative deadlines) and handle them gracefully.

1. Clarify requirements and constraints

Ask about the scheduling goal (e.g., maximize number of tasks, minimize maximum lateness), whether tasks can be preempted, if multiple machines are allowed, and any constraints on task durations.

2. Choose an appropriate algorithm

For maximizing number of tasks on a single machine, use a greedy approach: sort tasks by deadline and use a min-heap to keep track of selected tasks, replacing the longest task if a deadline is missed. For weighted tasks, consider dynamic programming.

3. Walk through an example

Trace the algorithm on a small example to verify correctness and demonstrate understanding of edge cases, such as tasks with the same deadline or tasks that cannot be scheduled.

4. Analyze complexity and optimize

State the time complexity (e.g., O(n log n) due to sorting and heap operations) and space complexity (O(n)). Discuss potential improvements or alternative approaches if needed.

5. Implement and test

Write clean, modular code with clear variable names, and test with edge cases (empty list, single task, all tasks missed). Be prepared to explain your code and handle follow-up questions.

Key Points to Mention

  • Greedy algorithm with sorting by deadline and using a min-heap (or max-heap) to select tasks.
  • Time complexity: O(n log n) for sorting and heap operations; space complexity: O(n).
  • Handling edge cases: empty input, tasks with equal deadlines, tasks with deadlines that are impossible to meet.
  • Alternative approaches: dynamic programming for weighted tasks or when the objective is different.
  • Real-world considerations: preemption, multiple machines, and task durations.
  • Clear communication: stating assumptions, explaining trade-offs, and writing testable code.

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