Fixed drawing bug with degenerate case of N=1 when reading from text file

PercolationVisualizer.java

/****************************************************************************
 *  Compilation:  javac PercolationVisualizer.java
 *  Execution:    java PercolationVisualizer input.txt
 *  Dependencies: Percolation.java StdDraw.java In.java
 *
 *  This program takes the name of a file as a command-line argument.
 *  From that file, it
 *
 *    - Reads the grid size N of the percolation system.
 *    - Creates an N-by-N grid of sites (intially all blocked)
 *    - Reads in a sequence of sites (row i, column j) to open.
 *
 *  After each site is opened, it draws full sites in light blue,
 *  open sites (that aren't full) in white, and blocked sites in black,
 *  with with site (0, 0) in the upper left-hand corner.
 *
 ****************************************************************************/

import java.awt.Font;

public class PercolationVisualizer {
    // delay in miliseconds (controls animation speed)
    private final static int delay = 100;

    // draw N-by-N percolation system
    public static void draw(Percolation perc, int N) {
        StdDraw.clear();
        StdDraw.setPenColor(StdDraw.BLACK);
        StdDraw.setXscale(0, N);
        StdDraw.setYscale(0, N);
        StdDraw.filledSquare(N/2.0, N/2.0, N/2.0);

        // draw N-by-N grid
        int opened = 0;
        for (int row = 0; row < N; row++) {
            for (int col = 0; col < N; col++) {
                if (perc.isFull(row, col)) {
                    StdDraw.setPenColor(StdDraw.BOOK_LIGHT_BLUE);
                    opened++;
                }
                else if (perc.isOpen(row, col)) {
                    StdDraw.setPenColor(StdDraw.WHITE);
                    opened++;
                }
                else
                    StdDraw.setPenColor(StdDraw.BLACK);
                StdDraw.filledSquare(col + 0.5, N - row - 0.5, 0.45);
            }
        }

        // write status text
        StdDraw.setFont(new Font("SansSerif", Font.PLAIN, 12));
        StdDraw.setPenColor(StdDraw.BLACK);
        StdDraw.text(.25*N, -N*.025, opened + " open sites");
        if (perc.percolates()) StdDraw.text(.75*N, -N*.025, "percolates");
        else                   StdDraw.text(.75*N, -N*.025, "does not percolate");

    }

    // file input
    private static void simulateFromFile(String filename) {
        In in = new In(filename);
        int N = in.readInt();
        Percolation perc = new Percolation(N);

        // turn on animation mode
        StdDraw.show(0); 

        // repeatedly read in sites to open and draw resulting system
        draw(perc, N);
        StdDraw.show(delay);
        while (!in.isEmpty()) {
            int i = in.readInt();
            int j = in.readInt();
            perc.open(i, j);
            draw(perc, N);
            StdDraw.show(delay);
        }
    }

    // random input
    private static void simulateFromRandom(int N) {
        // repeatedly generate sites at random and draw resulting system
        Percolation perc = new Percolation(N);
        PercolationVisualizer.draw(perc, N);
        while (!perc.percolates()) {
            StdDraw.show(0);          // turn on animation mode
            int i = StdRandom.uniform(N);
            int j = StdRandom.uniform(N);
            if (!perc.isOpen(i, j)) {
                perc.open(i, j);
                draw(perc, N);
                StdDraw.show(delay);
            }
        }
    }

    public static void main(String[] args) {
        if (args.length >= 2) throw new RuntimeException("Command line argument should be a filename or integer");
        else if (args.length == 0) simulateFromRandom(10);
        else {
            try {
                int N = Integer.parseInt(args[0]);
                simulateFromRandom(N);
            }
            catch (NumberFormatException e) {
                String filename = args[0];
                simulateFromFile(filename);
            }
        }
    }
}