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  1. #include <iostream>
  2. #include <stdlib.h>
  3. using namespace std;
  4.  
  5. /* structure for a node */
  6. struct node
  7. {
  8.     int data;
  9.     struct node *next;
  10.     node() : data(0), next(NULL){};
  11. };
  12.  
  13. /* Function to insert a node at the begining of a Circular
  14.    linked list */
  15. void push(struct node **head_ref, int data)
  16. {
  17. 	struct node *ptr = (struct node*)malloc(sizeof(struct node));
  18. 	ptr->data = data;
  19. 	ptr->next = *head_ref;
  20. 	struct node *temp = *head_ref;
  21. 	 /* If linked list is not NULL then set the next of last node. 
  22. 	 	It is going to last node by circling 1 times.
  23. 	 */
  24. 	if(*head_ref != NULL){
  25. 		while(temp->next != *head_ref){
  26. 			temp = temp->next;
  27. 		}
  28. 		//set last node by ptr
  29. 		temp->next = ptr;
  30. 	}
  31. 	else{
  32. 		// 1 node circular linked list
  33. 		ptr->next = ptr;
  34. 	}
  35. 	// after push ptr is the new node
  36. 	*head_ref = ptr;
  37. }
  38.  
  39. //get the previous node
  40. struct node* getPreviousNode(struct node* current_node){
  41. 	struct node* prev = current_node;
  42. 	while(prev->next != NULL && prev->next->data != current_node->data ){
  43. 		prev = prev->next;
  44. 	}
  45. 	return prev; 
  46. }
  47.  
  48.  
  49. /* Given a reference (pointer to pointer) to the head of a list
  50.    and a key, deletes the first occurrence of key in linked list */
  51. void deleteNodeByKey(struct node **head_ref, int key)
  52. {
  53. 	node dummy;
  54. 	dummy.next = *head_ref;
  55.  
  56. 	// Store head node
  57.     struct node* current_node = &dummy, *prev = &dummy;
  58. 	current_node = current_node->next;
  59.  
  60.     while(current_node->next != NULL && current_node->data != key){
  61.     	prev = prev->next;
  62. 		current_node = current_node->next;
  63.     }
  64.  
  65.     if(current_node == NULL){
  66.     	return;
  67.     }
  68.  
  69.  
  70.     // 11->2->56->12
  71.     //Removing the node 
  72.     prev->next = current_node->next;
  73.     current_node->next = NULL;
  74.     free(current_node);
  75.     *head_ref = dummy.next;
  76.     return;
  77.  
  78. }
  79.  
  80.  
  81. /* Function to print nodes in a given Circular linked list */
  82. void printList(struct node *head)
  83. {
  84. 	struct node *temp = head;
  85. 	if(head != NULL){
  86. 		/*
  87. 			do-while because at 1st temp points head 
  88. 			and after 1 rotation temp wil come back to head again
  89. 		*/
  90. 		do{
  91. 			cout<<temp->data<<' ';
  92. 			temp = temp->next;
  93. 		}
  94. 		while(temp != head);
  95. 		cout<<endl;
  96. 	}
  97. }
  98.  
  99. int main() {
  100. 	 /* Initialize lists as empty */
  101.     struct node *head = NULL;
  102.     /* Created linked list will be 11->2->56->12 */
  103.     push(&head, 12);
  104.     push(&head, 56);
  105.     push(&head, 2);
  106.     push(&head, 11);
  107.     cout<<"Contents of Circular Linked List"<<endl;
  108.     printList(head);
  109.  
  110.     deleteNodeByKey(&head, 11);
  111.     printList(head);
  112.  
  113. 	return 0;
  114. }
Success #stdin #stdout 0s 16064KB
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Standard input is empty
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Contents of Circular Linked List
11 2 56 12 
2 56 12 0
https://ideone.com/HQhZk4
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

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