Create CircularDoublyLinkedList.c

Author: gabrielmotablima

C/Data-Structures/LinkedList/CircularDoublyLinkedList.c

@@ -0,0 +1,286 @@
+/*****************************************************************
+ * Circular Doubly Linked List
+ *
+ * Algorithm explanation:
+ * A double-linked circular list is a data structure made up of
+ * nodes. Each node has two pointers that point to the previous
+ * node and the next node in the circular list.
+ *
+ *****************************************************************/
+#include <stdio.h>
+#include <stdlib.h>
+
+// structure of a node
+typedef struct list
+{
+ double value; ///< value stored in the node
+ struct list *next, *prev; ///< next/previous node pointing
+} List;
+
+// create list function
+List *create(double value)
+{
+ List *new_list = (List *)malloc(sizeof(List));
+ new_list->value = value;
+ new_list->next = new_list;
+ new_list->prev = new_list;
+ return new_list;
+}
+
+// insert a value at the beginning of the list
+List *insertBegin(List *list, double value)
+{
+ if (list == NULL)
+ list = create(value);
+ else
+ {
+ List *new_node = create(value);
+ new_node->next = list;
+ new_node->prev = list->prev;
+ list->prev->next = new_node;
+ list->prev = new_node;
+ list = new_node;
+ }
+ return list;
+}
+
+// insert a value at the end of the list
+List *insertEnd(List *list, double value)
+{
+ if (list == NULL)
+ list = create(value);
+ else
+ {
+ List *new_node = create(value);
+ new_node->next = list;
+ new_node->prev = list->prev;
+ list->prev->next = new_node;
+ list->prev = new_node;
+ }
+ return list;
+}
+
+// insert a value after other value in the list
+List *insertAfter(List *list, double new_value, double value)
+{
+ if (list == NULL)
+ list = create(value);
+ else
+ {
+ List *new_node = create(new_value), *prior = list;
+
+ while (prior->value != value && prior != list->prev)
+ prior = prior->next;
+
+ if (prior->value == value)
+ {
+ new_node->next = prior->next;
+ new_node->prev = prior;
+ prior->next->prev = new_node;
+ prior->next = new_node;
+ }
+ }
+ return list;
+}
+
+// insert a value by position in the list
+List *insertPos(List *list, double value, int pos)
+{
+ if (list == NULL)
+ list = create(value);
+
+ // positive position case
+ if (pos > 0)
+ {
+ // first position case
+ if (pos == 1)
+ return insertBegin(list, value);
+
+ int it = 1;
+ List *prior = list;
+
+ while (it != pos && prior != list->prev)
+ {
+ prior = prior->next;
+ it++;
+ }
+
+ // position in list range case
+ if (it + 2 > pos)
+ {
+
+ // last position case
+ if (prior == list->prev && it < pos)
+ list = insertEnd(list, value);
+
+ // general case
+ else
+ {
+ List *new_node = create(value);
+ new_node->next = prior;
+ new_node->prev = prior->prev;
+ prior->prev->next = new_node;
+ prior->prev = new_node;
+ }
+ }
+ }
+ return list;
+}
+
+// delete a value at the beginning in the list
+List *deleteBegin(List *list)
+{
+ if (list != NULL)
+ {
+ List *tmp = list;
+ list = list->next;
+ tmp->prev->next = list;
+ list->prev = tmp->prev;
+ }
+ return list;
+}
+
+// delete a value at the end in the list
+List *deleteEnd(List *list)
+{
+ if (list != NULL)
+ {
+ List *tmp = list->prev;
+ tmp->prev->next = list;
+ list->prev = tmp->prev;
+ }
+ return list;
+}
+
+// delete a value after other value in the list
+List *deleteAfter(List *list, double value)
+{
+ if (list != NULL)
+ {
+ List *prior = list;
+ while (prior->value != value && prior != list->prev)
+ prior = prior->next;
+
+ if (prior != list->prev && prior->value == value)
+ {
+ List *tmp = prior->next;
+ tmp->next->prev = prior;
+ prior->next = tmp->next;
+ }
+ }
+ return list;
+}
+
+// delete value by position in the list
+List *deletePos(List *list, int pos)
+{
+ if (list != NULL)
+ {
+ // first position case
+ if (pos == 1)
+ return deleteBegin(list);
+
+ List *prior = list;
+ int it = 1;
+
+ while (it != pos && prior != list->prev)
+ {
+ prior = prior->next;
+ it++;
+ }
+
+ // last position case
+ if (prior == list->prev && it == pos)
+ list = deleteEnd(list);
+
+ // general case
+ else
+ {
+ List *tmp = prior->next;
+ prior->prev->next = tmp;
+ tmp->prev = prior->prev;
+ }
+ }
+ return list;
+}
+
+// search value function, `1` to exists and `0` to doesn't exist
+int search(List *list, double value)
+{
+ if (list != NULL)
+ {
+ List *last_node = list->prev, *it = list;
+ while (it != last_node)
+ {
+ if (it->value == value)
+ return 1;
+ it = it->next;
+ }
+ if (it->value == value)
+ return 1;
+ return 0;
+ }
+}
+
+// print the circular doubly linked list
+void display(List *list)
+{
+ if (list != NULL)
+ {
+ List *it = list;
+ printf("\n...->");
+ if (it == list->prev)
+ printf("%f<-...", it->value);
+ else
+ {
+ while (it != list->prev)
+ {
+ printf("%f<->", it->value);
+ it = it->next;
+ }
+ printf("%f<->", it->value);
+ printf("<-...\n");
+ }
+ }
+}
+
+// example function, it shows up how the code works.
+void example()
+{
+ List *my_list = NULL;
+
+ my_list = create(0);
+ display(my_list);
+
+ my_list = insertBegin(my_list, 3);
+ display(my_list);
+
+ my_list = insertAfter(my_list, 2, 3);
+ display(my_list);
+
+ my_list = insertEnd(my_list, 5);
+ display(my_list);
+
+ my_list = insertPos(my_list, 100, 3);
+ display(my_list);
+
+ my_list = deleteBegin(my_list);
+ display(my_list);
+
+ my_list = deleteEnd(my_list);
+ display(my_list);
+
+ my_list = deleteAfter(my_list, 100);
+ display(my_list);
+
+ my_list = deletePos(my_list, 1);
+ display(my_list);
+
+ printf("\n%d\t%d", search(my_list, 100), search(my_list, 0));
+}
+
+int main()
+{
+ example();
+ return 0;
+}