Create SelfLoopLinkedList.c div-bargali#185

Create SelfLoopLinkedList.c

Author: div-bargali

C/Data-Structures/LinkedList/SelfLoopLinkedList.c

@@ -0,0 +1,105 @@
+#include <stdio.h> 
+#include <stdlib.h> 
+ 
+/* Link list node */
+struct Node { 
+ int data; 
+ struct Node* next; 
+}; 
+ 
+/* Function to remove loop. Used by detectAndRemoveLoop() */
+void removeLoop(struct Node*, struct Node*); 
+ 
+/* This function detects and removes loop in the list 
+ If loop was there in the list then it returns 1, 
+ otherwise returns 0 */
+int detectAndRemoveLoop(struct Node* list) 
+{ 
+ struct Node *slow_p = list, *fast_p = list; 
+ 
+ while (slow_p && fast_p && fast_p->next) { 
+ slow_p = slow_p->next; 
+ fast_p = fast_p->next->next; 
+ 
+ /* If slow_p and fast_p meet at some point then there 
+ is a loop */
+ if (slow_p == fast_p) { 
+ removeLoop(slow_p, list); 
+ 
+ /* Return 1 to indicate that loop is found */
+ return 1; 
+ } 
+ } 
+ 
+ /* Return 0 to indeciate that ther is no loop*/
+ return 0; 
+} 
+ 
+/* Function to remove loop. 
+ loop_node --> Pointer to one of the loop nodes 
+ head --> Pointer to the start node of the linked list */
+void removeLoop(struct Node* loop_node, struct Node* head) 
+{ 
+ struct Node* ptr1; 
+ struct Node* ptr2; 
+ 
+ /* Set a pointer to the beginning of the Linked List and 
+ move it one by one to find the first node which is 
+ part of the Linked List */
+ ptr1 = head; 
+ while (1) { 
+ /* Now start a pointer from loop_node and check if it ever 
+ reaches ptr2 */
+ ptr2 = loop_node; 
+ while (ptr2->next != loop_node && ptr2->next != ptr1) 
+ ptr2 = ptr2->next; 
+ 
+ /* If ptr2 reahced ptr1 then there is a loop. So break the 
+ loop */
+ if (ptr2->next == ptr1) 
+ break; 
+ 
+ /* If ptr2 did't reach ptr1 then try the next node after ptr1 */
+ ptr1 = ptr1->next; 
+ } 
+ 
+ /* After the end of loop ptr2 is the last node of the loop. So 
+ make next of ptr2 as NULL */
+ ptr2->next = NULL; 
+} 
+ 
+/* Function to print linked list */
+void printList(struct Node* node) 
+{ 
+ while (node != NULL) { 
+ printf("%d ", node->data); 
+ node = node->next; 
+ } 
+} 
+ 
+struct Node* newNode(int key) 
+{ 
+ struct Node* temp = (struct Node*)malloc(sizeof(struct Node)); 
+ temp->data = key; 
+ temp->next = NULL; 
+ return temp; 
+} 
+ 
+/* Drier program to test above function*/
+int main() 
+{ 
+ struct Node* head = newNode(50); 
+ head->next = newNode(20); 
+ head->next->next = newNode(15); 
+ head->next->next->next = newNode(4); 
+ head->next->next->next->next = newNode(10); 
+ 
+ /* Create a loop for testing */
+ head->next->next->next->next->next = head->next->next; 
+ 
+ detectAndRemoveLoop(head); 
+ 
+ printf("Linked List after removing loop \n"); 
+ printList(head); 
+ return 0; 
+}