Java Antwalk - 2D陣列

Question

有一個尺寸為9x9的2D數組。 螞蟻從細胞（5,5）或中心開始。 它隨機向北，向南，向東或向西移動。 當螞蟻從柵格上掉下來時，它會停止行走。 它落下的空間用X標記。在矩陣中，它應該顯示螞蟻訪問每個細胞的次數以及螞蟻脫落的移動次數。

我不知道從哪里開始或如何去做。 喜歡如何制作北，南，西，東方法。

這是我到目前為止所擁有的。

public static void main(String [] args)
{
    int [][] grid = new int[9][9];

    for (int r = 0; r< grid.length; r++)
    {
        for (int c = 0 ; c<grid[0].length; c++)
        {
            grid[r][c] = 0;
        }
    }

    boolean test = true;
    while(test)
    {
        int random =  (int)Math.random()*4+1;
        if (random == 1)
        {

        }
        else if (random == 2)
        {

        }
        else if (random == 3)
        {

        }
        else if (random == 4)
        {

        }
    }
}

Answer 1

你有正確的想法，現在你要做的是按隨機指定的方向移動，並增加數組中的值。 我就是這樣做的。

int count = 0;
int x = 4;
int y = 4; // arrays are 0 based
while(true)
{
    int random =  (int)Math.random()*4+1;
    if (random == 1)
    {
        x--; // move left
    }
    else if (random == 2)
    {
        x++; // move right
    }
    else if (random == 3)
    {
        y--; // move down
    }
    else if (random == 4)
    {
        y++; // move up
    }
    if(x < 0 || y < 0 || x >= grid.length || y >= grid[x].length) break;
    count++;
    grid[x][y]++;
}
System.out.println(count); // number of moves before it fell

Answer 2

這是一個螞蟻在網格上的隨機游走。 請參閱代碼中的注釋。 螞蟻在預定義的大小網格上行走STEPS。

import java.util.Random;

public class Ants {

    /** height and width of the grid */
    public static final int HEIGHT = 9 ;
    public static final int WIDTH  = 9 ;

    /** NOVAL means "no value" */
    public static final int NOVAL  = -1;

    /** world directions */
    public static final int NORTH  = 0 ;
    public static final int WEST   = 1 ;
    public static final int SOUTH  = 2 ;
    public static final int EAST   = 3 ;

    /** how many steps for ant to walk */
    public static final int STEPS   = 10;

    /** where does the ant start it's walk */
    public static final int START_X = 5;
    public static final int START_Y = 5;

    /** printing related */
    public static final String ANT  = "ANT";

    private static final Random random = new Random();

    /** grid for ant to walk on */
    static int[] grid;

    /** get height of the grid */
    static int getHeight() {
        return HEIGHT;
    }

    /** get width of the grid */
    static int getWidth() {
        return WIDTH;
    }

    /** size of the grid */
    static int getSize() {
        return getWidth()*getHeight();
    }

    /** coordinates are converted to one dimension */
    /** @return index from coordinates. */
    static int idx(int x, int y) {
        return y*getWidth() + x;
    }

    /** get x coordinate of idx */
    static int x(int idx) {
        return idx % getWidth();
    }

    /** get y coordinate of idx */
    static int y(int idx) {
        return (idx - x(idx)) / getWidth();
    }

    /** get cell */
    static int getCell(int idx) {
        return grid[idx];
    }
    static int getCell(int x, int y) {
        return getCell(
                idx(x,y));
    }

    static void setCell(int idx, int value) {
        grid[idx] = value;
    }

    /** init array with some value */
    private static void initArr(int[] arr, int value) {
        for (int i = 0; i < arr.length; i++) {
            arr[i] = value;
        }
    }

    /**
     * @return adjancted cells indexes.
     */
    public static int[] adjanctedTo(int idx) {
        int[] adj = new int[4];
        initArr(adj, NOVAL);

        int x = x(idx);
        int y = y(idx);

        /** Is North available? */
        if (y - 1 >= 0) {
            adj[NORTH] = idx(x,y-1);
        }
        /** West? */
        if (x - 1 >= 0) {
            adj[WEST] = idx(x-1, y);
        }
        /** South? */
        if (y + 1 < getHeight()) {
            adj[SOUTH] = idx(x,y+1);
        }
        /** East? */
        if (x + 1 < getWidth()) {
            adj[EAST] = idx(x+1, y);
        }

        return adj;
    }

    /** picks random value from array */
    public static int pick(int[] arr) {
        int ret = NOVAL;
        int idx = random.nextInt(4);

        for (int i = idx;; i++) {
            if (NOVAL != arr[i]) {
                ret = arr[i];
                break;
            }
            if (3 == i) {
                /** cycle if not yet found a NOVAL value in array */
                i = 0;
            }
        }

        return ret;
    }

    public static void main(String[] args) {

        /** init grid */
        grid = new int[getSize()];

        int nextStep = NOVAL;
        int current  = idx(START_X, START_Y);
        setVisited(current);

        for (int s = 0; s < STEPS; s++) {
            System.out.println("STEP "+s);
            System.out.println(
                    "Standing @" + position(current) + ".");
            printGrid(current);

            nextStep = pick(
                    adjanctedTo(current));

            System.out.println(
                    "Moving to " + position(nextStep));
            setVisited(current);
            printGrid(nextStep);

            current = nextStep;
        }
    }

    public static void setVisited(int idx) {
        setCell(idx, getCell(idx)+1);
    }

    public static String position(int idx) {
        return idx+"("+x(idx) + ";" + y(idx) +")";
    }

    public static void printGrid(int antPosition) {
        for (int x = 0; x < getWidth(); x++) {
            for (int y = 0; y < getHeight(); y++) {
                if (idx(x,y) == antPosition) { 
                    System.out.print(ANT);
                } else {
                    System.out.format(
                            "%2d|",
                            getCell(x,y));
                }
            }
            System.out.println();
        }
    }

}