SquarePrinter

import java.awt.Point;

/**
 * Oh, you thought creating squares is easy?!
 * Not here, no way!
 *
 */
public class Challenge1 {

    public static void main(String[] args) {
        // I'm too lazy to check if arguments are formatted correctly
        // do that yourself!
        int size = Integer.parseInt(args[0]);
        if(size % 2 == 0 || size < 0) {
            System.err.println("Input must be an odd positive number");
            System.exit(1);
        }

        printSquare(size);
    }


    /**
     * Print sweet squares such as this
     *
     * 111 112 113 114 115 116 117 118 119 120 121
     * 110  73  74  75  76  77  78  79  80  81  82
     * 109  72  43  44  45  46  47  48  49  50  83
     * 108  71  42  21  22  23  24  25  26  51  84
     * 107  70  41  20   7   8   9  10  27  52  85
     * 106  69  40  19   6   1   2  11  28  53  86
     * 105  68  39  18   5   4   3  12  29  54  87
     * 104  67  38  17  16  15  14  13  30  55  88
     * 103  66  37  36  35  34  33  32  31  56  89
     * 102  65  64  63  62  61  60  59  58  57  90
     * 101 100  99  98  97  96  95  94  93  92  91
     *
     * whaaaaat how did he do that? will this get me all the ladies? let's wait and see!
     *
     * @param size
     */
    private static void printSquare(int size) {

        // initialize arrays
        int[][] square = new int[size][];

        for(int line = 0; line < size; line++) {
            square[line] = new int[size];
        }

        // current position, direction to walk to
        Point pos = new Point(size / 2, size / 2);
        Point dir = new Point(1, 0);

        // change direction based on step count
        // first two times turn right on every single step
        // then two times on every second step (done through incrementing stepReset by 2)
        // then two times on every third step...
        int stepReset = 2;
        int stepCount = stepReset;

        for(int num = 1; num <= size * size; num++) {
            square[pos.y][pos.x] = num;
            pos.translate(dir.x, dir.y);

            // if step count is half of stepReset or 0, turn right
            stepCount--;
            if(stepCount % (stepReset / 2) == 0) {
                int tmp = dir.x;
                dir.x = -dir.y;
                dir.y = tmp;

                // turned right twice with same length
                // add 1 to the amount of steps it takes to turn right again
                if(stepCount == 0) {
                    stepReset += 2;
                    stepCount = stepReset;
                }
            }
        }

        // right align numbers. if longest number has three digits, 1 will be displayed as "  1"
        String digits = "%" + ((int) Math.log10(size * size) + 1) + "d ";
        for(int[] y : square) {
            for(int x : y) {
                System.out.printf(digits, x);
            }

            System.out.println();
        }
    }
}