What or unexpected behavior are you currently running into?
: To get the alternating pattern, we check if the sum of the current row and column indices is even ( (i + j) % 2 == 0 ). If it is, we assign that spot a Example: At board[0][0] (even), so it becomes board[0][1] (odd), so it stays print_board
Happy coding! 🧩
Now that we have the logic for determining the color of each square, let's add the code to draw the squares. We can use the rect function to draw a square at a specific position.
if ((row + col) % 2 == 0) grid.set(row, col, Color.red); else grid.set(row, col, Color.black); Use code with caution. Copied to clipboard 4. Display the result 9.1.7 Checkerboard V2 Codehs
To create a checkerboard, a cell should be a 1 if the sum of its row and column indices is even (or odd, depending on your starting preference). : Assign 1 . Odd sum : Assign 0 . Step-by-Step Implementation
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Inside the inner loop, calculate the position (x and y) for the current square. Use an if/else statement to decide the color. The Logic for Alternating Colors
: The (r + c) % 2 trick is the industry standard for creating grid patterns—it’s much cleaner than using multiple if/else statements for odd/even rows. What or unexpected behavior are you currently running into
A checkerboard alternates on both axes. The formula (row + col) % 2 is the golden rule.
Using this formula ensures that the pattern automatically shifts correctly at the start of every new row without requiring messy nested conditional state trackers. Step-by-Step Code Implementation
The core of the pattern is the alternating sequence for each row. You can use Python's list multiplication to create the pattern for a single row, which will be repeated to form the full board:
By adding the row index and column index (i + j) , you create a diagonal wave of even and odd numbers: 0+0 = 0 ( Even ) → 1 Row 0, Col 1: 0+1 = 1 ( Odd ) → 0 Row 1, Col 0: 1+0 = 1 ( Odd ) → 0 Row 1, Col 1: 1+1 = 2 ( Even ) → 1 Alternative Approach: Even vs Odd Rows You can also think about it row by row: Even rows (0, 2, 4...) start with 1 . Odd rows (1, 3, 5...) start with 0 . ⚠️ Common Pitfalls in CodeHS 🧩 Now that we have the logic for
You are expected to create an empty list (or a list filled with zeros) and then use nested loops to assign 1 s to the correct positions based on the (row + col) index sum 1.2.4 . The Logic Behind the Board
To recreate this programmatically, you must analyze the relationship between the row index and the column index. The Mathematical Logic Behind Checkerboards
: Instead of checking just the column index, we look at the sum of the row and col indices. If (row + col) % 2 == 0 , color the square red . Otherwise, color it black .