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) | |
1
public 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 //走之前初始化地图.
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,无法执行.");
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(".")) //第一步也要画
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(".")) //第一步也要画
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(".")) //第一步也要画
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 2005-11-28 10:32
鱼上游 阅读(1068)
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