9.1.6 Checkerboard V1 Codehs May 2026

This document analyzes the problem titled "9.1.6 checkerboard v1" from CodeHS (assumed exercise naming), reconstructs likely requirements, explains correct algorithmic approaches, provides a rigorous step‑by‑step solution, proves correctness, highlights edge cases, and offers an annotated reference implementation in Python (readable pseudocode for educators/students). Assumptions about the exact original prompt are made explicit where the source problem text is unavailable.

def checkerboard(n, a="X", b=" "):
    # n: board dimension (nonnegative int)
    # a, b: tokens for even and odd parity cells
    for r in range(n):
        line_chars = []
        for c in range(n):
            if (r + c) % 2 == 0:
                line_chars.append(a)
            else:
                line_chars.append(b)
        print("".join(line_chars))

Notes:

Graphical sketch (pseudo for CodeHS turtle-like API):

def draw_checkerboard(n, square_size, color1, color2):
    for r in range(n):
        for c in range(n):
            color = color1 if (r + c) % 2 == 0 else color2
            draw_filled_square(x=c*square_size, y=r*square_size, size=square_size, fill=color)

CodeHS Exercise 9.1.6: Checkerboard, v1 , the primary goal is to create a 2D list (a "grid") representing a checkers board using 1s for pieces and 0s for empty squares. Exercise Objectives Grid Initialization 9.1.6 checkerboard v1 codehs

: 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

: Use a loop to append three rows, each containing eight 1s. Fill the Middle Rows : Append two rows of eight 0s. Fill the Bottom Rows : Append another three rows of eight 1s. Function Call : Pass the completed list to the print_board Common Implementation Strategies Simple Append board.append([1] * 8)

within loops is the most straightforward method for version 1. Nested Loops This document analyzes the problem titled "9

: Some variations or autograders may require initializing the board with 0s first and then using nested loops to selectively assign to specific indices (e.g., board[i][j] = 1 Autograder Requirements : To pass all tests on , ensure you are using assignment statements

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

: Forgetting that the middle two rows (index 3 and 4 in an 8-row grid) must remain empty (0s). Bypassing Assignment Notes:

: Attempting to print the pattern directly instead of modifying the elements within a list structure. specific Python code

for these requirements, or are you looking for the logic behind Checkerboard v2

I’m unable to provide the exact code solution for “9.1.6 Checkerboard v1” from CodeHS, as that would violate academic integrity policies. However, I can give you a clear conceptual guide to help you write it yourself.

To solve this, you need to understand two fundamental concepts: