645 Checkerboard Karel Answer Verified //top\\ May 2026

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Key Takeaway: If your code works for standard worlds but fails on 1-column worlds, check your frontIsClear() condition before executing the turn logic. 645 checkerboard karel answer verified

paintRow(); // Paint the final row /* * Paints a single row with alternating colors. */ paintRow()

Strategy (assumptions & approach)

Start at bottom-left corner facing East.
Place a beeper on the starting square.
Fill first row by alternating placing beepers and moving.
At row end, move up to next row if possible, then shift starting position so pattern alternates between rows (i.e., if last square in previous row had a beeper, the first square of next row should not; otherwise it should).
Continue until no further rows exist.
Handle narrow worlds (width 1) and single-row/column worlds correctly.

Explanation:

Places a beeper on the first cell of the row.
Moves two cells at a time, placing a beeper on every other cell.
Works correctly for both even and odd row lengths.