Codehs - 9.1.7 Checkerboard V2

Nested Loops

This problem is a classic introduction to and Modular Arithmetic . It asks you to draw a checkerboard pattern where the color of each square depends on its position (row and column).

Understanding the Problem

Goal:

Draw a checkerboard pattern using alternating colored squares (usually black and red or black and white). The board should have 8 rows and 8 columns. However, V2 typically introduces two key requirements: 9.1.7 Checkerboard V2 Codehs

• Each row has 8 columns.
• isBlack is toggled 8 times per row.
• 8 is even, so after the inner loop, isBlack returns to the same value it had at the start of that row.
• But the next row should start with the opposite color.
• Therefore, after each row, we must manually toggle isBlack once more if COLS is even.

Mistake #2: Off-by-One Errors

• Canvas size: 400x400
• Square size: 50x50 (since 8 * 50 = 400)

# This is the logic for the checkerboard pattern: # If the sum of the row and column indices is even, make it red. # Otherwise, make it black. if (row + col) % 2 == 0: pen.color("red") else: pen.color("black") Nested Loops This problem is a classic introduction

• pen.speed(0): This is highly recommended. Drawing 64 squares one by one takes a long time at normal speed. Setting speed to 0 makes the turtle draw instantly, which is crucial for testing your code quickly in the CodeHS editor.

System.out.println(); // new line after each row Each row has 8 columns