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IBM·Software Engineer·Online Assessment (OA)·Junior

JuniorPrefer not to say
Jul 2026Remote

Summary

IBM OA, 90 minutes, two questions. One greedy problem and one heap problem. Pretty standard format, nothing too wild.

Questions Asked (2)

Q1

Solve a greedy algorithm problem.

Algorithms & Data Structures
Author's notes

No details shared about the specific problem, just that it was greedy-based.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the problem and identifying the greedy choice property and optimal substructure. Then propose a greedy strategy, justify its correctness with an exchange argument, and analyze time/space complexity. Finally, discuss edge cases and potential pitfalls.

Pro tip: Always articulate why a greedy approach works here—interviewers at IBM value rigorous correctness proofs, not just code. If unsure, mention that you'd verify with a counterexample or consider dynamic programming as a fallback.

1. Understand and clarify the problem

Ask questions to confirm input/output, constraints, and edge cases. Restate the problem in your own words to ensure alignment.

2. Identify greedy choice and optimal substructure

Explain why a local optimal choice leads to a global optimum. Discuss the greedy choice property and optimal substructure.

3. Propose a greedy algorithm

Outline the steps of the algorithm, including sorting or data structures if needed. Walk through a small example to illustrate.

4. Prove correctness

Use an exchange argument or induction to show the greedy algorithm yields an optimal solution. Address why other approaches might fail.

5. Analyze complexity and edge cases

State time and space complexity. Discuss edge cases (e.g., empty input, ties) and how the algorithm handles them.

Key Points to Mention

  • Greedy choice property and optimal substructure
  • Exchange argument for correctness proof
  • Time and space complexity analysis
  • Edge cases and constraints handling
  • Comparison with dynamic programming or other paradigms
  • Real-world applications or examples

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

Q2

Solve a heap-based problem.

Algorithms & Data Structures
Author's notes

Heap question, no specifics given.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the problem requirements and constraints, then explain the heap-based solution, including the choice of min-heap or max-heap and the algorithm's steps. Walk through a small example to illustrate, and analyze time and space complexity.

Pro tip: Demonstrate deep understanding by discussing trade-offs between heap and other data structures, and mention real-world applications like priority queues or streaming median.

1. Clarify the problem

Ask questions to confirm input format, output requirements, constraints, and edge cases. Ensure you understand what the heap is used for.

2. Choose the right heap type

Decide between min-heap and max-heap based on whether you need the smallest or largest elements efficiently. Justify your choice.

3. Outline the algorithm

Describe step-by-step how to use the heap to solve the problem, including initialization, insertion, extraction, and any additional data structures.

4. Walk through an example

Pick a small input and trace the algorithm, showing heap operations and intermediate states to verify correctness.

5. Analyze complexity and edge cases

State time and space complexity, and discuss how the solution handles edge cases like empty input or duplicate values.

Key Points to Mention

  • Heap property and operations (insert, extract-min/max, heapify) with time complexities
  • Choice between min-heap and max-heap and why it matters
  • Time and space complexity analysis (e.g., O(n log k) for top-k problems)
  • Comparison with alternative approaches (e.g., sorting, quickselect) and trade-offs
  • Handling edge cases such as empty input, single element, or all duplicates
  • Real-world applications of heaps (e.g., priority queues, Dijkstra's algorithm, streaming median)

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