fork(1) download 
  1. /**
  2.  * Folding LInked List 
  3.  * @author PRATEEK
  4.  */
  5.  class FoldList {
  6.  
  7. 	static Node foldList(Node head)
  8. 	{
  9. 		return fold(head,head);
  10. 	}
  11.  
  12. private static Node fold(Node head, Node curr) {
  13. 		if (curr == null)
  14. 			return head;
  15.  
  16. 		Node result = fold(head, curr.next);
  17.  
  18. 		// condition to stop execution if result is head and curr is not the
  19. 		// last node
  20. 		if (result != head || curr.next == null) 
  21. 		{
  22. 			// handling odd and even number of nodes
  23. 			if (result != curr && result.next!=curr) 
  24. 			{
  25. 				curr.next = result.next;
  26. 				result.next = curr;
  27. 				return curr.next;
  28. 			}
  29. 			curr.next = null;
  30. 		}
  31. 		return head;
  32. 	}
  33.  
  34. 	public static void displayList(Node head) {
  35. 		Node tempNode;
  36. 		tempNode = head;
  37. 		while (tempNode != null) {
  38. 			System.out.print(tempNode.data + "-->");
  39. 			tempNode = tempNode.next;
  40. 		}
  41. 		System.out.print("null");
  42. 		System.out.println();
  43. 	}
  44.  
  45. 	public static void main(String[] args) {
  46. 		Node root = new Node(1);
  47. 		root.next = new Node(2);
  48. 		root.next.next = new Node(3);
  49. 		root.next.next.next = new Node(4);
  50. 		root.next.next.next.next = new Node(5);
  51. 		root.next.next.next.next.next = new Node(6);
  52. 		root.next.next.next.next.next.next = new Node(7);
  53. 		displayList(root);
  54. 		displayList(foldList(root));
  55.  
  56. 	}
  57. }
  58.  
  59. /**
  60.  * Linked List Node
  61.  * @author Prateek
  62.  */
  63. class Node {
  64.  
  65. 	public int data;
  66. 	public Node next;
  67. 	public Node prev;
  68.  
  69. 	public Node(int data) {
  70. 		this.data = data;
  71. 	}
  72.  
  73. 	public String toString() {
  74. 		return ""+this.data;
  75. 	}
  76. }
Success #stdin #stdout 0.07s 380160KB
comments (?)
stdin 
Standard input is empty
stdout 
1-->2-->3-->4-->5-->6-->7-->null
1-->7-->2-->6-->3-->5-->4-->null
https://ideone.com/PSkisx
Folding of LInked List
language:
Java (HotSpot 12)
created:
10 years ago
visibility:
public

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