Ensure your while loops have a clear exit condition ( frontIsClear() or leftIsClear() ).
# 1. Initialize the board with all 0s board = [] for i in range(8): board.append([0] * 8) # 2. Use nested loops to replace 0s with 1s # Goal: Top 3 and bottom 3 rows should have 1s in a checkerboard pattern for row in range(8): for col in range(8): # Check if it's in the top 3 (0-2) or bottom 3 (5-7) rows if row < 3 or row > 4: # Use modulus to create the alternating checkerboard pattern if (row + col) % 2 == 0: board[row][col] = 1 # 3. Print the final board for row in board: print(row) Use code with caution. Copied to clipboard Why this works:
For the CodeHS exercise , the goal is to initialize a
Create two distinct row-planting functions: putRow() (starts with a ball) and putRowRows() (starts with a move). 2. The Fencepost Error (Off-by-One)
Mastering the 916 Checkerboard v1: Solutions and Logic for CodeHS 916 checkerboard v1 codehs fixed
GRect square = new GRect(x, y, SQUARE_SIZE, SQUARE_SIZE); square.setFilled(true);
Getting stuck on this exercise is incredibly common. A single misplaced index or a misunderstood loop boundary can easily break your grid. This guide breaks down the logic, provides a clean and fixed solution, and explains exactly how the code works. Understanding the Checkerboard Logic
To get your code fixed and working in the CodeHS editor, you need to use to traverse the grid. The outer loop manages the rows, and the inner loop manages the columns within each row.
The beauty of the Checkerboard, v1 exercise is that it distills complex visual tasks into simple, logical components. By mastering this foundation, you’re equipping yourself with the core skills to tackle far more complex programming challenges in the future. Happy coding Ensure your while loops have a clear exit
Let’s break down exactly how the code works:
You need an outer loop for rows and an inner loop for columns.
This code initializes an 8x8 grid of zeros and then fills the top three and bottom three rows with a checkerboard pattern of 1s.
def next_row(): turtle.penup() turtle.backward(400) turtle.right(90) turtle.forward(50) turtle.left(90) turtle.pendown() Use nested loops to replace 0s with 1s
Define a function that iterates through each row of your 2D list. Use a list comprehension to convert the integers to strings so they can be joined by spaces for the final display. 4. Avoid Common Errors
If your CodeHS autograder is failing, you are likely running into one of three frequent issues. 1. The "Reversed Row" Bug
The solution provided in this guide will pass the CodeHS autograder, as it correctly creates an 8x8 board with pieces placed only in the top three and bottom three rows. Use this guide as a learning tool to understand the concepts, not just to copy code, and you will be well on your way to becoming a proficient programmer.
This is where most students run into errors. Standard buggy code often tries to alternate elements by flipping a boolean flag after every iteration. However, flag-flipping breaks down when a row ends, because the first cell of the next row needs to match or alternate based on the grid geometry, not just the previous cell.
Here is the clean, fixed solution for the . This version uses constants to make it easy to adjust the size. javascript