Coursera - Computer Science: Programming With A Purpose

Week 4: Input And Output - Checkerboard

Jul 1, 2020

Write a program Checkerboard.java that takes a command-line integer n and plots an n-by-n checkerboard pattern to standard drawing. Color the squares blue and light gray, with the bottom-left square blue. To draw,

Call StdDraw.setScale(0, n) so that x- and y-coordinates of the canvas range from 0 and n.
Call either StdDraw.filledSquare() or StdDraw.filledPolygon() to draw each of the n² squares.
Make sure that the squares fit snugly in the standard drawing window.
Do not change the canvas size.

~/Desktop/io> javac Checkerboard.java

~/Desktop/io> java Checkerboard 8

~/Desktop/io> java Checkerboard 4

~/Desktop/io> java Checkerboard 5

Note: the above description is copied from Coursera and converted to markdown for convenience

Solution:

public class Checkerboard {

    public static void main(String[] args) {
        final int n = Integer.parseInt(args[0]);

        StdDraw.setScale(0, n);
        for (int row = 0; row < n; row++) {
            for (int col = 0; col < n; col++) {
                if (row % 2 == 0) {
                    if (col % 2 == 0) {
                        StdDraw.setPenColor(Color.BLUE);
                    } else {
                        StdDraw.setPenColor(Color.LIGHT_GRAY);
                    }
                } else {
                    if (col % 2 == 0) {
                        StdDraw.setPenColor(Color.LIGHT_GRAY);
                    } else {
                        StdDraw.setPenColor(Color.BLUE);
                    }
                }
                StdDraw.filledSquare(col + 0.5, row + 0.5, 0.5);
            }
        }
    }
}

Link To: Java Source Code