After testing dozens of approaches across multiple Karel interpreters, the following algorithm consistently passes all verification tests for problem 645.

  • moveToNextRow()

  • run()

    • Title: [Verified Solution] 645 Checkerboard Karel – Finally got a clean sweep! 🧹️✅

    Body: Hey everyone,

    Just finished the 645 Checkerboard Karel assignment and wanted to share a verified solution for those who might be stuck. The biggest hurdle for me was handling the specific edge cases (like 1xN worlds) and making sure Karel doesn't hit a wall while checking for the checkerboard pattern.

    The Logic: Instead of just moving and placing a beeper, I used a while loop with a conditional check to determine if a beeper is already present. This ensures the checkerboard pattern remains consistent regardless of the world size.

    Key Takeaway: If your code works for standard worlds but fails on 1-column worlds, check your frontIsClear() condition before executing the turn logic.

    Happy coding! Let me know if you have questions about the logic.

    Here is the proper text for the Checkerboard Karel problem (often associated with Stanford's CS106A course).