Stanford編程方法學公開課作業 2 ---- Karel中生成棋盤的代碼

解決如下圖所示問題：（生成間隔棋盤狀圖案）

要求程序可以在 各類形狀的地圖中正常運行（如1x8 8x1 5x6 6x6 7x7 等等）

 

代碼如下：

1. /*
2. * File: CheckerboardKarel.java
3. * ----------------------------
4. * The CheckerboardKarel class is able to draw
5. * a checkerboard using beepers, as described in Assignment 1. You
6. * should make sure that your program works for all of the sample
7. * worlds supplied in the starter folder.
8. */
10. import stanford.karel.*;
12. public class CheckerboardKarel extends SuperKarel {
14. public void run() {
15. goToOrigin();
16. genReferenceRow(); //generate a reference row, choose 1st row as reference
17. toFaceNorth(); //to face north
18. while ( frontIsClear() ) {
19. if ( beepersPresent() ) {
20. moveToNextRow();
21. if ( frontIsClear() ) {
22. move();
23. genReferenceRow();
24. } //to deal with world with only one column
25. } else {
26. moveToNextRow();
27. genReferenceRow();
28. }
29. toFaceNorth();
30. } //end of while loop
32. } //end of main method
35. /*
36. * Make Karel move to the next row without changing column number
37. * Karel is always moving toward north part
38. * Precondition: facing north
39. * Postcondition: facing east/west depending on Karel is standing on
40. * left end or right end
41. */
42. private void moveToNextRow() {
43. if ( leftIsBlocked() ) { //at left end wall of the world
44. move();
45. turnRight(); //to face east
46. } else { //at right end wall of the world
47. move();
48. turnLeft(); //to face west
49. } // end of if-else
50. } // end of moveToNextRow()
52. /*
53. * Is defined to generate one row of beepers, beepers are exactly 2 units apart
54. * Precondition: any case
55. * Postcondition: arrive at the end of one row
56. */
57. private void genReferenceRow() {
58. if ( frontIsBlocked() ) {
59. putBeeper(); //dealing with the world with only one column
60. }
61. while ( frontIsClear() ) {
62. putBeeper();
63. move(); //enter while means can move forward at least one step
64. if ( frontIsClear() ) {
65. //if width is even, second move could not be made
66. move(); //second move
67. //if width is odd, second move should make, one beeper should be added
68. //in front of wall
69. if ( frontIsBlocked() ) {
70. putBeeper();
71. }
72. }
73. }
74. }
77. /*Move Karel back to origin of map (1,1), make it facing east
78. * Precondition: can be any case
79. * Postcondition: standing on (1,1) facing east
80. */
81. private void goToOrigin() {
82. while (notFacingSouth()) {
83. turnLeft();
84. }
85. moveToWall();
86. while (notFacingWest()) {
87. turnLeft();
88. }
89. moveToWall();
90. while (notFacingEast()) {
91. turnLeft(); //Karel will face east
92. }
93. }
95. private void moveToWall() { //move Karel to wall
96. while (frontIsClear()) {
97. move();
98. }
99. }
101. private void toFaceNorth() {
102. while ( notFacingNorth() ) {
103. turnLeft();
104. }
105. }
106. }