fork download 
  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7. /* Name of the class has to be "Main" only if the class is public. */
  8. class MyList
  9. {
  10. 	public final Object head;
  11. 	public final MyList tail;
  12. 	private MyList(Object head, MyList tail)
  13. 	{
  14. 		this.head = head;
  15. 		this.tail = tail;
  16. 	}
  17. 	public static MyList cons(Object head, MyList tail)
  18. 	{
  19. 		if (head == null)
  20. 			return tail;
  21. 		else if (head instanceof MyList)
  22. 			return cons(((MyList)head).head, cons(((MyList)head).tail, tail));
  23. 		else
  24. 			return new MyList(head, tail);
  25. 	}
  26. 	public static MyList reverse(MyList list)
  27. 	{
  28. 		if (list == null)
  29. 			return null;
  30. 		else
  31. 			return cons(reverse(list.tail), new MyList(list.head, null));
  32. 		// [3, [4, [5, null]]]:
  33. 		// cons(reverse([4, [5, null]]), [3, null])
  34. 		// cons([5, 4, null], [3, null])
  35. 		// cons([5, cons([4, null], [3, null])])
  36. 		// cons(5, [4, [3, null]])
  37. 		// [5, [4, [3, null]]]
  38. 	}
  39. 	public static void printMyList(MyList list, String format)
  40. 	{
  41. 		MyList current = list;
  42. 		while (current != null)
  43. 		{
  44. 			System.out.printf(format, current.head);
  45. 			current = current.tail;
  46. 		}
  47. 		System.out.println();
  48. 	}
  49. 	public static void main (String[] args) throws java.lang.Exception
  50. 	{
  51. 		MyList numbers = MyList.cons(1,
  52. 			MyList.cons(2,
  53. 				MyList.cons(3,
  54. 					MyList.cons(4,
  55. 						MyList.cons(5, null)
  56. 					)
  57. 				)
  58. 			)
  59. 		);
  60. 		printMyList(numbers, "%2d");
  61. 		printMyList(reverse(numbers), "%2d");
  62. 	}
  63. }
Success #stdin #stdout 0.11s 320576KB
comments (?)
stdin 
Standard input is empty
stdout 
 1 2 3 4 5
 5 4 3 2 1
https://ideone.com/QfSSxu
language:
Java (HotSpot 12)
created:
9 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!