TopCoder--镜子反射路径问题.

矩阵中' ` ' 左斜的镜子＼,  ' / ' 为右斜的镜子／. 光路是 - | 和 + .自己运行一下看看吧!

package topcoder;

/*
 * Created on 2005-12-1
 * @author Admin.zhouyuan
 */

public class MirrorPath
{
    private int direction; // 向下走为0，向右走为1，向上走为2， 向左走为3
    private int row;
    private int col;

    public String[] path(String[] map)
    {
        findExit(map);
        char[][] ch = new char[map.length][map[0].length()];
        for (int i = map.length - 1; i >= 0; i--)
            for (int j = map[0].length() - 1; j >= 0; j--)
            {
                ch[i][j] = map[i].charAt(j);
            }
        System.out.println("row = " + this.row + "; col = " + this.col + "; direction = " + direction);
        while (row >= 0 && row < map.length && col >= 0 && col < map[0].length())
        {
            switch (this.direction)
            {
                case 0:
                    switch (ch[row][col])
                    {
                        case '.':
                            ch[row][col] = '|';
                            ++row;
                            break;
                        case '-':
                            ch[row][col] = '+';
                            ++row;
                            break;
                        case '`':
                            direction = 1;
                            ++col;
                            break;
                        case '/':
                            direction = 3;
                            --col;
                            break;
                    }
                    // System.out.println("0");
                    break;

                case 1:
                    switch (ch[row][col])
                    {
                        case '.':
                            ch[row][col] = '-';
                            ++col;
                            break;
                        case '|':
                            ch[row][col] = '+';
                            ++col;
                            break;
                        case '`':
                            direction = 0;
                            ++row;
                            break;
                        case '/':
                            direction = 2;
                            --row;
                            break;
                    }
                    // System.out.println("1");
                    break;

                case 2:
                    switch (ch[row][col])
                    {
                        case '-':
                            ch[row][col] = '+';
                            --row;
                            break;
                        case '.':
                            ch[row][col] = '|';
                            --row;
                            break;
                        case '`':
                            direction = 3;
                            --col;
                            break;
                        case '/':
                            direction = 1;
                            ++col;
                            break;
                    }
                    // System.out.println("2");
                    break;

                case 3:
                    switch (ch[row][col])
                    {
                        case '|':
                            ch[row][col] = '+';
                            --col;
                            break;
                        case '.':
                            ch[row][col] = '-';
                            --col;
                            break;
                        case '`':
                            direction = 2;
                            --row;
                            break;
                        case '/':
                            direction = 0;
                            ++row;
                            break;
                    }
                    break;
            }
        }
        for (int i = map.length - 1; i >= 0; i--)
            map[i] = new String(ch[i]);
        return map;
    }

    private void findExit(String[] map)
    {
        int i = map.length - 1;
        int j = map[0].length() - 1;
        for (; i > 0; i--)
        {
            if (map[i].charAt(0) != '#')
            {
                this.direction = 1;
                this.row = i;
                this.col = 0;
                return;
            }
            else
                if (map[i].charAt(j) != '#')
                {
                    this.direction = 3;
                    this.row = i;
                    this.col = j;
                    return;
                }
        }

        i = map.length - 1;
        j = map[0].length() - 1;
        for (; j >= 0; j--)
        {
            if (map[0].charAt(j) != '#')
            {
                this.direction = 0;
                this.row = 0;
                this.col = j;
                return;
            }
            else
                if (map[map.length - 1].charAt(j) != '#')
                {
                    this.direction = 2;
                    this.col = j;
                    this.row = i;
                    return;
                }
        }

        // System.out.println("direction = " + this.direction);
        return;
    }

    public static void main(String[] args)
    {
        MirrorPath mp = new MirrorPath();
        /*
         * String[] str = new String[]{ "############", "#######/....", "######//####", "#####//#####", "####//######",
         * "..../#######", "############" };
         *
         * String[] str = new String[]{ "###########.#", "#/........./.", "#.#########.#", "#`........./#",
         * "#############" };
         *
         * String[] str = new String[]{ "########.##", "#./......`#", "#../.`....#", "#.`...../.#", "#....`.../#",
         * "###.#######" };
         */
        String[] str = new String[] { "##.########", "#.........#", "..`.`.....#", "#..`......#", "#.`.`.`...#", "#....`....#",
                "#...`.`.`.#", "#.........#", "#.....`./.#", "#.........#", "###########" };
        for (int i = 0; i < str.length; i++)
        {
            System.out.println(str[i]);
        }
        mp.path(str);
        for (int i = 0; i < str.length; i++)
        {
            System.out.println(str[i]);
        }
    }
}