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  1. #include<iostream>
  2. using namespace std;
  3.  
  4. class Node {
  5. public:
  6. 	int data;
  7. 	Node* next; //this pointer, will store the address of the next node
  8. 	Node* prev;
  9. 	Node(int val) {
  10. 		data = val;
  11. 		next = NULL; //NULL means nothing, not pointing to anything
  12. 	}
  13. };
  14.  
  15. Node* revLL(Node* head) {
  16. 	// Initializing three pointers
  17. 	Node* prev = NULL;
  18. 	Node* curr = head;
  19. 	Node* next = NULL;
  20.  
  21. 	// Iterating through the linked list
  22. 	while (curr != NULL) {
  23. 		// Storing the next node
  24. 		next =  curr->next;
  25. 		// Updating the next pointer of curr to prev
  26. 		curr->next = prev;
  27. 		// Updating prev as curr and curr as next
  28. 		prev = curr;
  29. 		curr = next;
  30. 	}
  31.  
  32. 	// prev now points to the new head of the reversed list
  33. 	return prev;
  34. }
  35.  
  36. void printLL(Node* node) {
  37.  
  38. 	while (node != NULL) {
  39. 		// So I print the current node value
  40. 		cout << node->data <<" ";
  41. 		// Then I move to the next node
  42. 		node = node->next;
  43. 	}
  44. 	cout<<endl;
  45. }
  46.  
  47. void AddAtEnd(Node* head, int val){
  48. 	//I want to add a new node, at the end of my LL
  49.  
  50.  
  51. 	// Create a new node
  52. 	Node* newNode = new Node(val);
  53.  
  54. 	// Go to the last node
  55. 	Node* curr = head;
  56. 	while(curr->next != NULL) { // because the last element's next will be NULL
  57. 		curr = curr->next;
  58. 	}
  59.  
  60. 	// Now, It is pointing to the last element
  61. 	// Point the next of the last node to new node.
  62.  
  63. 	curr->next = newNode;
  64. }
  65.  
  66. int main() {
  67. 	Node* head = new Node(1);
  68. 	// head->next = new Node(2);
  69. 	// head->next->next = new Node(3);
  70. 	// head->next->next->next = new Node(4);
  71.  
  72. 	AddAtEnd(head, 2);
  73. 	AddAtEnd(head, 3);
  74. 	AddAtEnd(head, 4);
  75. 	AddAtEnd(head, 5);
  76. 	AddAtEnd(head, 6);
  77.  
  78. 	cout << "Given linked list: ";
  79. 	printLL(head);
  80.  
  81. 	head = revLL(head);
  82.  
  83. 	cout << "Reversed linked list: ";
  84. 	printLL(head);
  85.  
  86. 	return 0;
  87. }
Success #stdin #stdout 0.01s 5292KB
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stdin
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Standard input is empty
stdout
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Given linked list: 1 2 3 4 5 6 
Reversed linked list: 6 5 4 3 2 1
https://ideone.com/GMa7WC
Reverse a Linked list
language:
C++14 (gcc 8.3)
created:
11 days ago
visibility:
public

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