if the prompt specifically requests them, as simply printing the pattern without storing it in a grid may cause errors. Typical Pitfalls Incorrect Function Placement : Defining the print_board function inside another block or incorrectly indenting it. Missing Middle Rows
: Create a 2D integer array with 8 rows and 8 columns.
To create the offset pattern, look at the coordinates of the grid indices (Row, Column): Row 0, Col 0 →right arrow Color A (0 + 0 = 0, Even) Row 0, Col 1 →right arrow Color B (0 + 1 = 1, Odd) Row 1, Col 0 →right arrow Color B (1 + 0 = 1, Odd) Row 1, Col 1 →right arrow Color A (1 + 1 = 2, Even)
CodeHS Exercise 9.1.6 (Checkerboard, v1) requires creating an 8x8 grid, utilizing nested loops to populate top and bottom rows with 1s in alternating positions while leaving middle rows as 0s. The solution initializes a 2D list and applies an assignment statement to update specific cells where the sum of the row and column indices is odd. For detailed code solutions, review the answers at 9.1.6 checkerboard v1 codehs
for i in range(8): row = [] for j in range(8): # Check if the sum of row and column indices is even if (i + j) % 2 == 0: row.append("red") else: row.append("black") board.append(row)
9.1.6 Checkerboard v1 CodeHS: Full Implementation Guide The exercise in CodeHS challenges you to create a classic 8x8 checkerboard pattern using JavaScript and the CodeHS graphics library. This assignment is a milestone in learning computer science because it forces you to combine nested loops, coordinate geometry, and conditional logic.
This is the most efficient way to handle alternating patterns in programming. if the prompt specifically requests them, as simply
The mathematical secret to this pattern is the . If you add the row index and the column index Even sums result in one color. Odd sums result in the other color. The Code Implementation
The outer loop ( row ) handles the vertical movement, while the inner loop ( col ) handles the horizontal movement. This ensures every single "coordinate" on the board is visited. 2. The Modulo Operator (%) The code (row + col) % 2 == 0 is the engine of the program. At (0,0) , the sum is 0. 0 % 2 is 0 (Even). At (0,1) , the sum is 1. 1 % 2 is 1 (Odd). At (1,0) , the sum is 1. 1 % 2 is 1 (Odd). At (1,1) , the sum is 2. 2 % 2 is 0 (Even).
# Function to print the board in the required format def print_board(board): for row in board: # Join the numbers with a space print(" ".join(map(str, row))) def main(): # 1. Initialize an empty board with 8 rows and 8 columns of zeros board = [] for i in range(8): board.append([0] * 8) # 2. Modify the board: Set specific elements to 1 # Example logic: Make top 3 rows all 1s for row in range(3): for col in range(8): board[row][col] = 1 # Alternatively, you can fill the whole board with a checkerboard # or specific pattern, but 3 rows of 1s is a common requirement. # 3. Print the resulting board print_board(board) main() Use code with caution. 4. Key Takeaways for Success A. List Initialization To create the offset pattern, look at the
if (row + col) % 2 == 0: evaluates the grid position. For example: Row 0, Col 0: →right arrow Row 0, Col 1: →right arrow Row 1, Col 0: →right arrow
function start() // Define the size of the board var NUM_ROWS = 8; var NUM_COLS = 8; // Outer loop handles the rows for (var row = 0; row < NUM_ROWS; row++) // Inner loop handles the columns for (var col = 0; col < NUM_COLS; col++) // Check if the sum of row and col is even if ((row + col) % 2 == 0) drawSquare(row, col, Color.red); else drawSquare(row, col, Color.black); function drawSquare(row, col, color) var sideLength = getWidth() / 8; var x = col * sideLength; var y = row * sideLength; var rect = new Rectangle(sideLength, sideLength); rect.setPosition(x, y); rect.setColor(color); add(rect); Use code with caution. Key Components Explained 1. Nested Loops
: If the sum leaves a remainder, it colors the square white . Visual Example Matrix (Row + Col) : Top-Left cell (0,0) : →right arrow Next cell right (0,1) : →right arrow First cell second row (1,0) : →right arrow Second cell second row (1,1) : →right arrow 3. Calculating Coordinates
: Create an 8x8 grid (list of lists) representing a game board. Specific Pattern top 3 rows bottom 3 rows should contain 1s. middle 2 rows should contain only 0s. Output Requirement : Use a provided print_board function to display the grid in a human-readable format. Key Logical Steps Initialize the Board : Create an empty list, typically named Fill the Top Rows
This version explicitly creates each element in the 2D list.