9.1.7 Checkerboard V2 Codehs ★

console.log(line);

@.@.@ .@.@. @.@.@ .@.@. @.@.@ const readline = require('readline'); const rl = readline.createInterface( input: process.stdin, output: process.stdout ); rl.question("Rows: ", (rows) => rl.question("Cols: ", (cols) => rows = parseInt(rows); cols = parseInt(cols); for (let i = 0; i < rows; i++) let line = ""; for (let j = 0; j < cols; j++) if ((i + j) % 2 === 0) line += "X"; else line += "O"; 9.1.7 Checkerboard V2 Codehs

Introduction If you are currently working through the CodeHS Java (or JavaScript) curriculum , particularly the unit on Nested Loops or 2D Arrays , you have likely encountered the infamous exercise: 9.1.7 Checkerboard V2 . console

1. Off-by-One Errors in Parity Wrong: if (row % 2 == 0) — This creates stripes, not a checkerboard. Fix: Always use (row + col) % 2 == 0 . 2. Hardcoding Dimensions The "V2" often implies a variable board size. If the autograder tests with 10x10 and your code only works for 8x8, you will fail. Fix: Use constants or user input at the top of your function. 3. Incorrect Starting Color If the expected output starts with a dark square at (0,0), ensure your if branch matches that. Swap colors if needed. 4. Graphical Version – Gaps Between Squares Using setFilled(true) alone might leave a tiny border. Some CodeHS exercises expect setFilled(true) without setColor for the outline. If gaps appear, set the outline color to match the fill color: System.out.print("Enter number of rows: ")

private static final int NUM_ROWS = 8; private static final int NUM_COLS = 8;

System.out.print("Enter number of rows: "); int rows = input.nextInt(); System.out.print("Enter number of columns: "); int cols = input.nextInt(); for (int i = 0; i < rows; i++) for (int j = 0; j < cols; j++) if ((i + j) % 2 == 0) System.out.print("@"); else System.out.print("."); System.out.println(); // new line after each row

Whether you are printing text to the console or drawing colored rectangles on a canvas, the logic remains identical. Write your code to be flexible (no magic numbers), test edge cases (1 row or 1 column), and always double-check your starting color.