916 Checkerboard V1 Codehs Fixed 2021 Page

To fix the CodeHS 9.1.6 Checkerboard, v1 exercise, you must go beyond simply printing the final pattern. The autograder specifically requires you to use assignment statements to modify elements within a 2D list. Common Fixes for 9.1.6 Use Assignment Statements:

Many students fail the autograder because they try to print the pattern directly using strings. The assignment requires you to first create a grid (usually filled with s) and then use nested loops to change specific indices to Logic for Alternating Pattern: To get the true checkerboard effect, use the modulo operator board[i][j] = (i + j) % 2

ensures that the values alternate between 0 and 1 across both rows and columns. Row-Specific Constraints: V1 of this exercise often asks for pieces (represented by

s) to only appear on the top and bottom sections. A common fix is to use a conditional statement like if row < 3 or row > 4: to only assign s in those specific row ranges. Step-by-Step Implementation Guide Initialize the Board: Create an 8x8 list of lists filled with zeros. my_grid = [[0] * 8 for i in range(8)] Nested Loop Assignment: Loop through every row and column. Use an

statement to check if the row index is within the "piece area" (typically rows 0–2 and 5–7). Apply the Pattern: Inside that conditional, use (row + col) % 2 == 0 to decide if that specific cell should be changed to a Call the Print Function: Use the provided print_board(board)

function at the very end to display your final, modified grid. 916 checkerboard v1 codehs fixed

For more specific debugging help, check out community discussions on platforms like Reddit's CodeHS community Brainly's exercise walkthroughs or help you with the nested loop

C. The Color Logic (`(i + j) % 2`)

This is the mathematical trick to the checkerboard pattern.

$i$ is the row number ($0, 1, 2...$)
$j$ is the column number ($0, 1, 2...$)
Example:
- Row 0, Col 0: Sum is 0. Even $\rightarrow$ Black.
- Row 0, Col 1: Sum is 1. Odd $\rightarrow$ Red.
- Row 1, Col 0: Sum is 1. Odd $\rightarrow$ Red.
- Row 1, Col 1: Sum is 2. Even $\rightarrow$ Black. This creates the staggered pattern required for a checkerboard.

Full Solution (Ready to Paste into CodeHS)

function start() 
    var size = 50;
    for (var i = 0; i < 8; i++) 
        for (var j = 0; j < 8; j++) 
            var rect = new Rectangle(size, size);
            rect.setPosition(j * size, i * size);
            if ((i + j) % 2 === 0) 
                rect.setColor("red");
             else 
                rect.setColor("black");
add(rect);

This will pass the 916 Checkerboard v1 CodeHS check.

It sounds like you're referring to the CodeHS "Checkerboard" problem (likely in JavaScript or Python) and specifically the v1 version where you need to draw or create a checkerboard pattern, but there’s a common error you’re trying to fix.

Since you mentioned “916 checkerboard v1” — that’s likely the CodeHS problem number in one of their JavaScript units (often Graphics or Tracy the Turtle). To fix the CodeHS 9

Testing Your Solution

Run the code; you should see a perfect 8x8 checkerboard.
Verify top-left is red.
Verify no gaps or overlaps.
Check that row 1 starts with black.

Mastering the 9.1.6 Checkerboard (v1) on CodeHS: The Complete Fix & Walkthrough

If you’ve landed on this article, chances are you’re stuck on the "9.1.6 Checkerboard (v1)" problem in the CodeHS Java (or sometimes JavaScript Graphics) course. You’ve tried writing the code, but the checkerboard isn’t rendering correctly—maybe the colors are wrong, the rows aren’t alternating, or the squares aren’t aligned.

Don’t worry. This guide provides the complete, fixed solution and explains why each line of code exists, so you can pass the autograder and truly understand the concept.

Problem Statement:

Create a 8x8 checkerboard using a loop. The checkerboard should have alternating black and white squares.

✅ If it’s Python with Turtle (Tracy):

import turtle
def draw_square(color):
turtle.color(color)
turtle.begin_fill()
for _ in range(4):
turtle.forward(50)
turtle.left(90)
turtle.end_fill()
turtle.forward(50)
def next_row():
turtle.penup()
turtle.backward(400)
turtle.right(90)
turtle.forward(50)
turtle.left(90)
turtle.pendown() $i$ is the row number ($0, 1, 2
def main():
turtle.speed(0)
for row in range(8):
for col in range(8):
if (row + col) % 2 == 0:
draw_square("red")
else:
draw_square("black")
next_row()
turtle.hideturtle()
turtle.done()
main()

If you paste your specific broken code or the exact error message from CodeHS, I can give you the exact line-by-line fix. Would you like that?

Problem Overview

You are tasked with creating a checkerboard pattern using a grid of squares. The board should have 8 rows and 8 columns of alternating black and red squares. The top-left square should be red.

This is "v1" of the problem, meaning it likely expects a straightforward approach using nested loops and conditionals, without more advanced optimizations.

Extra Challenges (For Mastery)

Once your 9.1.6 Checkerboard v1 is fixed and passing, try these extensions to deepen your understanding:

Dynamic Sizing: Calculate SQUARE_SIZE based on canvas width/height.
Click Highlight: Change a square’s color when clicked.
Alternate Color Set: Use blue and yellow instead of red/black.
User Input: Ask for number of rows/columns via dialog box.