Merge pull request #746 from Monik09/DoubleLinkedListC

Added Double linked list[C]

Author: theyashshahs

doubly_linked_list/doublyLinkedList.c

@@ -0,0 +1,185 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+struct node
+{
+	int data;
+	struct node *next;
+	struct node *prev;
+};
+
+struct node *head = NULL, *last = NULL;
+
+struct node *createNode(int key)
+{
+	head = (struct node *)malloc(sizeof(struct node)); //allocate the required space to *node variable
+	head->data = key;
+	head->next = NULL;
+	head->prev = NULL;
+	last = head;
+	return head;
+}
+
+struct node *additionOfNodeAtBeginning(int key) //adding at the beginning of the linked list
+{
+	struct node *temp;
+	temp = (struct node *)malloc(sizeof(struct node));
+	temp->data = key;
+	temp->next = head; //making temp variable point to head of the linked list
+	temp->prev = NULL; //pointing the prev of temp to NULL pointer
+	head->prev = temp;
+	head = temp;
+	return head;
+}
+
+struct node *additionOfNodeAtEnding(int key) //adding the element at the last of the linked list
+{
+	struct node *temp;
+	temp = (struct node *)malloc(sizeof(struct node));
+	temp->data = key;
+	temp->next = NULL;
+	temp->prev = last;
+	last->next = temp;
+	temp->next = NULL;
+	last = temp;
+	return last;
+}
+
+struct node *additionOfNodeAtRandomeIndex(int key, int index) //adding the element at the given index
+{
+	struct node *temp;
+	temp = (struct node *)malloc(sizeof(struct node));
+	temp->data = key;
+	temp->next = NULL;
+	if (index == 0)
+	{
+		return additionOfNodeAtBeginning(key);
+	}
+	struct node *temp1, *temp2;
+	temp1 = head;
+	int i = 0;
+	//iterating through the list till the iterator variable is index or list is empty
+	while (i < index - 1 && temp1->next != NULL)
+	{
+		temp1 = temp1->next;
+		i++;
+	}
+	if (temp1->next == NULL)
+	{
+		additionOfNodeAtEnding(key);
+	}
+	temp2 = temp1->next;
+	temp->prev = temp1;
+	temp1->next = temp;
+	temp->next = temp2;
+	temp2->prev = temp;
+	return head;
+}
+
+struct node *deletingFromBeginning() //deleting the element at head
+{
+	struct node *temp;
+	temp = head;
+	head = head->next; //making the head pointer to point the element next to it
+	head->prev = NULL;
+	free(temp); //free the space occupied by former head pointer
+	return head;
+}
+
+struct node *deletingFromEnding() //deleting the element from the ending
+{
+	struct node *temp, *temp2;
+	temp = last->prev; //temp pointer pointing to the second last element of linked list
+	temp2 = last;	   //temp2 pointing to last element
+	temp->next = NULL;
+	last = temp; //make second last pointer as last element
+	free(temp2);
+	return head;
+}
+
+struct node *deletingFromRandomIndex(int index) //deleting the element from given index
+{
+	struct node *temp, *temp2;
+	temp = head;
+	int i = 0;
+	while (temp != NULL && i < index)
+	{
+		i++;
+		temp = temp->next;
+	}
+	if (index == 0)
+	{
+		return deletingFromBeginning();
+	}
+	else if (temp == last)
+	{
+		return deletingFromEnding();
+	}
+	else if (temp != NULL) //if temp is NULL the index is out of Bound
+	{
+		temp->prev->next = temp->next;
+		temp->next->prev = temp->prev;
+		free(temp);
+	}
+	else
+	{
+		printf("Index Out Of Bound\n"); //index is out of bound
+	}
+	return head;
+}
+
+void displayInReverse() //display the linked list in reverse order
+{
+	printf("the Linked List in Reverse Order is ");
+	struct node *temp = last; //creating iterator pointing to the last element
+	while (temp != NULL)
+	{
+		printf("%d ", temp->data);
+		temp = temp->prev;
+	}
+	printf("\n\n");
+}
+
+void display() //display the linked list
+{
+	printf("the Linked List is ");
+	struct node *temp = head; //creating iterator pointing to the head
+	while (temp != NULL)
+	{
+		printf("%d ", temp->data);
+		temp = temp->next;
+	}
+	printf("\n\n");
+}
+
+int main()
+{
+	struct node *root = NULL;
+	root = createNode(4); // creating the list
+
+	additionOfNodeAtBeginning(6); //adding the value 6 at beginning
+	additionOfNodeAtEnding(90);	  //adding value 90 at last
+	printf("After adding 90 at last ,");
+	display(); //display the list
+	//index are starting from 0
+	additionOfNodeAtRandomeIndex(12, 1); //adding 12 at index 1
+	printf("After adding 12 at index 1 ,");
+	display();
+	additionOfNodeAtBeginning(1);
+	additionOfNodeAtEnding(2);
+	additionOfNodeAtBeginning(5);
+	additionOfNodeAtEnding(98);
+	additionOfNodeAtRandomeIndex(122, 2); //index are starting from 0
+	display();
+	deletingFromBeginning(); //deleting the head element
+	printf("After Deletion from beginning, ");
+	display();
+	deletingFromEnding(); //deleting the last element from the list
+	printf("After deleting from end, ");
+	display();
+	deletingFromRandomIndex(3); //deleting the element at index 3(0 is starting index)
+	printf("After deleting from index 3 ,");
+	display();
+
+	displayInReverse(); //display the linked list in reverse order
+}