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Forked from mycodeschool/DoublyLinkedList.c
Created May 17, 2017 10:06
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Doubly Linked List implementation in C
/* Doubly Linked List implementation */
#include<stdio.h>
#include<stdlib.h>
struct Node {
int data;
struct Node* next;
struct Node* prev;
};
struct Node* head; // global variable - pointer to head node.
//Creates a new Node and returns pointer to it.
struct Node* GetNewNode(int x) {
struct Node* newNode
= (struct Node*)malloc(sizeof(struct Node));
newNode->data = x;
newNode->prev = NULL;
newNode->next = NULL;
return newNode;
}
//Inserts a Node at head of doubly linked list
void InsertAtHead(int x) {
struct Node* newNode = GetNewNode(x);
if(head == NULL) {
head = newNode;
return;
}
head->prev = newNode;
newNode->next = head;
head = newNode;
}
//Inserts a Node at tail of Doubly linked list
void InsertAtTail(int x) {
struct Node* temp = head;
struct Node* newNode = GetNewNode(x);
if(head == NULL) {
head = newNode;
return;
}
while(temp->next != NULL) temp = temp->next; // Go To last Node
temp->next = newNode;
newNode->prev = temp;
}
//Prints all the elements in linked list in forward traversal order
void Print() {
struct Node* temp = head;
printf("Forward: ");
while(temp != NULL) {
printf("%d ",temp->data);
temp = temp->next;
}
printf("\n");
}
//Prints all elements in linked list in reverse traversal order.
void ReversePrint() {
struct Node* temp = head;
if(temp == NULL) return; // empty list, exit
// Going to last Node
while(temp->next != NULL) {
temp = temp->next;
}
// Traversing backward using prev pointer
printf("Reverse: ");
while(temp != NULL) {
printf("%d ",temp->data);
temp = temp->prev;
}
printf("\n");
}
int main() {
/*Driver code to test the implementation*/
head = NULL; // empty list. set head as NULL.
// Calling an Insert and printing list both in forward as well as reverse direction.
InsertAtTail(2); Print(); ReversePrint();
InsertAtTail(4); Print(); ReversePrint();
InsertAtHead(6); Print(); ReversePrint();
InsertAtTail(8); Print(); ReversePrint();
}
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