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mycodeschool/DoublyLinkedList.c

Created November 12, 2013 11:38
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  1. mycodeschool created this gist Nov 12, 2013.
    87 changes: 87 additions & 0 deletions DoublyLinkedList.c
    View file
    Original file line number Diff line number Diff line change
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    /* 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();

    }