← Walmart Interview Insights

Walmart·Software Engineer·Onsite - Multi Round·Junior

JuniorPending
Jul 2026

Summary

Two back-to-back technical rounds at a big tech company as a freshman, one went well and one went sideways because I skipped studying trees and got a tree problem.

Questions Asked (2)

Q1

Solve a coding problem covering edge cases and communicate your thought process throughout.

Algorithms & Data Structures
Author's notes

First round, felt pretty good.

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AI HintsAI Generated

Suggested Approach

Start by restating the problem in your own words and asking clarifying questions to confirm assumptions and constraints. Then outline your approach, including the algorithm and data structures, before writing any code. While coding, verbalize your thoughts, and after writing, walk through edge cases and test your solution with examples.

Pro tip: Demonstrate a systematic approach to edge cases by categorizing them (e.g., empty input, single element, large input, duplicates) and explicitly testing each category. This shows thoroughness and reduces the chance of missing critical cases.

1. Understand and Clarify

Restate the problem in your own words and ask clarifying questions about input types, constraints, expected output, and edge cases. Confirm your understanding with the interviewer.

2. Plan and Communicate

Outline your approach, including the algorithm and data structures you'll use. Discuss time and space complexity, and consider alternative solutions. Get buy-in before coding.

3. Code with Narration

Write clean, modular code while explaining each step. Use meaningful variable names and handle edge cases as you go. Keep the interviewer engaged by verbalizing your thought process.

4. Test and Validate

Walk through your code with a normal case and several edge cases. Check for off-by-one errors, null inputs, and other pitfalls. If needed, debug and refine your solution.

5. Reflect and Optimize

If time permits, discuss potential optimizations or trade-offs. Summarize your solution and its complexity, and invite feedback from the interviewer.

Key Points to Mention

  • Clarifying questions to ensure alignment with interviewer expectations
  • Choice of data structures and their impact on time/space complexity
  • Edge cases: empty input, single element, duplicates, large input, invalid input
  • Step-by-step walkthrough of code logic
  • Testing strategy: normal cases, edge cases, and potential bugs
  • Time and space complexity analysis of the final solution

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

Q2

Solve a tree-based algorithm problem.

Algorithms & Data Structures
Author's notes

I made a bet that trees wouldn't come up based on what I'd seen from this company online.

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AI HintsAI Generated

Suggested Approach

Clarify the problem, then walk through a recursive or iterative tree traversal solution, explaining time and space complexity. Optimize by considering iterative approaches or pruning to handle large inputs typical in Walmart's scale.

Pro tip: Always discuss edge cases like empty trees, skewed trees, and duplicate values, and mention how you'd test your solution with unit tests. This shows production-level thinking beyond just solving the algorithm.

1. Clarify the Problem

Ask questions to confirm input format, output expectations, constraints (e.g., tree size, node values), and edge cases. This ensures you solve the right problem and demonstrates thoroughness.

2. Discuss Approaches

Propose a brute-force solution first, then optimize. For tree problems, consider DFS (recursive/iterative) or BFS, and analyze trade-offs in time/space complexity.

3. Code the Solution

Write clean, modular code with meaningful variable names. Explain your logic as you code, and handle edge cases explicitly.

4. Test with Examples

Walk through a few test cases, including edge cases, to verify correctness. If time permits, discuss how you would write unit tests.

5. Analyze Complexity and Optimize

State the time and space complexity of your solution. If possible, suggest further optimizations or alternative approaches for scalability.

Key Points to Mention

  • Tree traversal techniques: DFS (pre-order, in-order, post-order) and BFS
  • Recursion vs iteration and when to use each (e.g., stack overflow risk with deep trees)
  • Time and space complexity analysis (Big O notation)
  • Edge cases: empty tree, single node, skewed tree, duplicate values
  • Handling large inputs: iterative solutions, pruning, or tail recursion
  • Testing strategy: unit tests, boundary cases, and performance considerations

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