Cracking Walmart Labs General Coding Round: Sudoku & Nonogram Challenges

Software Engineering
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walmartlabs | General Software Engineer | Interview Experience

Interview Date: Not specified
Result: Not specified
Difficulty: Not specified

Interview Process

The interview consisted of multiple rounds, including a technical phone interview that was not completed in the first attempt and required a redo.

Technical Questions

  • Course Overlap
    Input: String[][] course = {{"17", "Math"}, {"17", "English"}, {"58", "Math"}, {"61", "Physics"}}
    Output: {"17,58", ["Math"], "17,61", [], "58,61", []}

  • Validate Sudoku
    Input:
    int[][] grid = {{1,2,3}, {2,3,1}, {3,1,2}}
    Output: true
    Input:
    int[][] grid = {{0,2,3}, {2,3,1}, {3,1,2}}
    Output: false
    Input:
    int[][] grid = {{1,3}, {2,1}}
    Output: false

  • Validate Nonogram
    Input:
    char[][] matrix1 = {{'W','W','W','W'}, {'B','W','W','W'}, {'B','W','B','B'}, {'W','W','B','W'}, {'B','B','W','W'}}
    int[][] rows1_1 = {{},{1},{1,2},{1},{2}}; int[][] columns1_1 = {{2,1},{1},{2},{1}}
    Output: true
    Input:
    int[][] rows1_2 = {{},{},{1},{1},{1,1}}; int[][] columns1_2 = {{2},{1},{2},{1}}
    Output: false

  • Spring Boot Questions

    • If many beans are application-scoped and memory keeps growing, what could be wrong?
    • How would you design a clean and maintainable dependency structure in a Spring Boot + Thymeleaf app?
    • If teams log in different ways and logs are hard to search, how would you fix it?
    • How do you safely manage different environments (dev/QA/prod) in Spring Boot?
    • For an elderly-friendly Spring Boot + Thymeleaf app, what UX or accessibility improvements would you use?
    • If users lose sessions or get logged out when switching secure pages, how would you debug and fix it?
    • If you need to run logic after request handling but before rendering the response, what Spring mechanism would you use?
    • How would you build a product list page with pagination and sorting in Spring Boot?
    • How would you handle long-running tasks in Spring Boot to avoid performance issues?
    • How do you design a Spring Boot app for high availability and load balancing?
    • We have a form that has complex validation rules. What steps would you take to ensure maintainability and a good user experience?
    • How does implicit navigation work in Spring Boot, and what considerations would you keep in mind when using them?

Tips & Insights

Focus on understanding Spring Boot’s core concepts and how to manage dependencies effectively. Practice solving algorithmic problems to prepare for technical interviews.