645 Checkerboard Karel Answer Verified May 2026

The solution to the 6.4.5 Checkerboard Karel challenge requires

The most critical part of the algorithm is the "Turn Around" logic. When Karel reaches a wall: 645 checkerboard karel answer verified

• They assume an even number of streets/avenues. Verified answers must work for odd dimensions.
• They place a beeper at the start of every row. This breaks the checkerboard pattern because row 2, column 1 should be empty if row 1, column 1 had a beeper.
• They use turnRight() without checking if the right is clear. This causes crashes on narrow worlds.
• They forget to handle the "single row" case. A loop expecting to move north will crash instantly.

left_is_clear(): transition_to_next_row() fill_row() # Place a beeper at the start if appropriate put_beeper() front_is_clear(): move() # Only move again and place a beeper if front is clear The solution to the 6

Single Column Worlds: If the world is only one column wide, Karel must be able to turn left and move up without trying to move East first. They assume an even number of streets/avenues