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			GOOGLE挑戰賽練習題1及答案(200分)
		
          
		
          Problem Statement 
          

          
     
A simple line drawing program uses a blank 20 x 20 pixel canvas and
a directional cursor that starts at the upper left corner pointing
straight down. The upper left corner of the canvas is at (0, 0) and the
lower right corner is at (19, 19). You are given a String[], commands,
each element of which contains one of two possible commands. A command
of the form "FORWARD x" means that the cursor should move forward by x
pixels. Each pixel on its path, including the start and end points, is
painted black. The only other command is "LEFT", which means that the
cursor should change its direction by 90 degrees counterclockwise. So,
if the cursor is initially pointing straight down and it receives a
single "LEFT" command, it will end up pointing straight to the right.
Execute all the commands in order and return the resulting 20 x 20
pixel canvas as a String[] where character j of element i represents
the pixel at (i, j). Black pixels should be represented as uppercase
'X' characters and blank pixels should be represented as '.'
characters. 
          

          


          Definition 
          

          
     


          


          
Class: 
DrawLines 
          

          
Method: 
execute 
          

          
Parameters: 
String[] 
          

          
Returns: 
String[] 
          

          
Method signature: 
String[] execute(String[] commands) 
          

          
(be sure your method is public) 
          

           
          

            1public class DrawLines
            2{
            3  class Pos
            4  {
            5    private int X;
            6    private int Y;
            7    private String status = ".";
            8
            9    public Pos(int x,int y)
           10    {
           11      this.X = x;
           12      this.Y = y;
           13      this.status = ".";
           14    }
           15
           16    public int getX()
           17    {
           18      return X;
           19    }
           20
           21    public int getY()
           22    {
           23      return Y;
           24    }
           25
           26    public void setX(int x)
           27    {
           28      this.X = x;
           29    }
           30
           31    public void setY(int y)
           32    {
           33      this.Y = y;
           34    }
           35
           36    public void setStatus(String s)
           37    {
           38      this.status = s;
           39    }
           40
           41    public String getSatus()
           42    {
           43      return status;
           44    }
           45
           46    public void showPos()
           47    {
           48      String xStr=X+"";
           49      String yStr=Y+"";
           50
           51      if(X<10)
           52      {
           53        xStr = "0"+xStr;
           54      }
           55
           56      if(Y<10)
           57      {
           58        yStr = "0"+yStr;
           59      }
           60    }
           61  }
           62
           63  public int min = 0, max = 19;
           64  public int North = 1, South = 3, West = 2, East = 0;
           65  public String LEFT = "LEFT", FORWARD = "FORWARD";
           66  public Pos[][] map = null;
           67
           68
           69
           70  public DrawLines()
           71 {
           72   this.direction = South;
           73   pos = new Pos(0,0);
           74
           75   //走之前初始化地圖.
           76   map = new Pos[max + 1][max + 1];
           77   for(int row = 0;row<=max;row++)
           78   {
           79     for(int col=0;col<=max;col++)
           80     {
           81       map[row][col] = new Pos(row,col);
           82     }
           83   }
           84 }
           85
           86  public void showMap()
           87  {for (int col = 0; col <= max; col++)
           88
           89    {
           90      for (int row = 0; row <= max; row++)
           91      {
           92        System.out.print(map[row][col].getSatus());
           93      }
           94      System.out.println(); 
           95    }
           96  }
           97
           98  private Pos pos = null;
           99  private int direction = South;
          100
          101  public Pos getPos()
          102  {
          103    return pos;
          104  }
          105  public void setPos(Pos pos)
          106  {
          107    this.pos = pos;
          108  }
          109  /**
          110   *
          111   * @param cmd
          112   */
          113  public void execute(String cmd)
          114  {
          115    if (cmd.equals("LEFT"))
          116    {
          117      Left();
          118    }
          119    else if (cmd.indexOf(FORWARD) >= 0)
          120    {
          121      int from = cmd.indexOf(FORWARD);
          122      String stepStr = cmd.substring(from + FORWARD.length());
          123      stepStr = stepStr.trim();
          124      int step = Integer.parseInt(stepStr);
          125      forward(step);
          126    }
          127    else
          128    {
          129      System.out.println("未知的命令,無法執行.");
          130    }
          131  }
          132
          133  public String[] execute(String[] cmds)
          134  {
          135    if (cmds != null)
          136    {
          137      for (int i = 0; i < cmds.length; i++)
          138      {
          139        execute(cmds[i]);
          140      }
          141    }
          142
          143    String[] rval = new String[20];
          144    String tempStr = "";
          145    for (int col = 0; col <= max; col++)
          146     {
          147       tempStr = "";
          148       for (int row = 0; row <= max; row++)
          149       {
          150          tempStr = tempStr + map[row][col].getSatus();
          151       }
          152        rval[col]=tempStr;
          153     }
          154     return rval;
          155
          156  }
          157
          158  public void Left()
          159  {
          160    direction = (direction + 1) % 4;
          161  }
          162
          163  public void forward(int step)
          164  {
          165    if (direction == South) //Y++
          166    {
          167      while (pos.getY() < max && step>0)
          168      {
          169        if (map[pos.getX()][pos.getY()].getSatus().equals(".")) //第一步也要畫
          170        {
          171          map[pos.getX()][pos.getY()].setStatus("*");
          172        }
          173        pos.setY(pos.getY() + 1);
          174        map[pos.getX()][pos.getY()].setStatus("*");
          175        map[pos.getX()][pos.getY()].showPos();
          176        step--;
          177      }
          178    }
          179    else if (direction == East) //X++
          180    {
          181      while (pos.getX() < max && step>0)
          182      {
          183        if (map[pos.getX()][pos.getY()].getSatus().equals(".")) //第一步也要畫
          184        {
          185          map[pos.getX()][pos.getY()].setStatus("*");
          186        }
          187        pos.setX(pos.getX() + 1);
          188        map[pos.getX()][pos.getY()].setStatus("*");
          189        map[pos.getX()][pos.getY()].showPos();
          190        step--;
          191      }
          192
          193    }
          194    else if (direction == North) //Y--
          195    {
          196      while (pos.getY() > min && step>0)
          197      {
          198        if (map[pos.getX()][pos.getY()].getSatus().equals(".")) //第一步也要畫
          199        {
          200          map[pos.getX()][pos.getY()].setStatus("*");
          201        }
          202        pos.setY(pos.getY() - 1);
          203        map[pos.getX()][pos.getY()].setStatus("*");
          204        map[pos.getX()][pos.getY()].showPos();
          205        step--;
          206      }
          207    }
          208    else if (direction == West ) //X--
          209    {
          210      while (pos.getX() > min && step>0)
          211      {
          212        if (map[pos.getX()][pos.getY()].getSatus().equals(".")) //draw the first step
          213        {
          214          map[pos.getX()][pos.getY()].setStatus("*");
          215        }
          216        pos.setX(pos.getX() - 1);
          217        map[pos.getX()][pos.getY()].setStatus("*");
          218        map[pos.getX()][pos.getY()].showPos();
          219        step--;
          220      }
          221    }
          222  }
          223
          224  public static void main(String[] args)
          225  {
          226    String[] cmds = { "FORWARD 19","LEFT","FORWARD 19", "LEFT","FORWARD 19","LEFT","FORWARD 17","LEFT","FORWARD 17","LEFT","FORWARD 17","LEFT","FORWARD 13","LEFT","FORWARD 13","LEFT","FORWARD 13","LEFT","FORWARD 13","LEFT","FORWARD 13","LEFT",};
          227
          228    DrawLines dl = new DrawLines();
          229
          230    dl.execute(cmds);
          231
          232    dl.showMap();
          233
          234  }
          235
          236}
          
		
          
			posted on 2006-02-13 21:36 Vincent.Chen 閱讀(3282) 評論(0)  編輯  收藏  所屬分類: 雜文 
		
          
	
          
	
	


	


          
	    
    




          








          

				

          




    







          
        
	




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