Circular Linked Lists

We have seen a Singular Linked List, a Double Linked List, now it's time to witness the Legen- wait for it- dary Circular Linked List. Which is basically a simple Linked list, the only difference being that the last node's Next pointer points to the head value of the Linked List.

Let us see how insertion happens in a circular linked list.

We can add a node in 4 ways-

  • Insertion in empty list
  • Insertion at the beginning of the list
  • Insertion at the end of the list
  • Insertion in between the nodes
 Insertion in empty list->

void addtoempty(Node *last, int data)

{

    if(last!=NULL)

        return last;

    Node* temp= new Node(data);

    last= temp;

    temp->next=last;

    return last;

}

Here we have linked this single node to itself.

Insertion at the beginning->

void addbegin(Node *last, int data)

{

    Node* temp= new Node(data);

    temp->next=last->next;

    last->next= temp;

    return last;

}

Here we have created a temp node, changed it's next pointer to that of last node's, later turned the next pointer of last to temp value.


Insertion at the end->

Very similar to how we insert at beginning, the only difference being is that we assign the new node value as the last node value

void addtoend(Node* last, int data)

{

    Node* temp= new Node(data);

    temp->next= last->next;

    last->next=temp;

    last=temp;

    return last;

}

Insertion in between nodes->

We first need to search the right place to insert the node to maintain sorted property in a Linked list and then insert after.

void between(Node* last, int data, int item)

{

    Node* temp, *p;

    p=last->next;

    //search the item

    do{

            if(p->data==item)

                    temp->data=data;

                    temp->next=p->next;

                    p->next=temp;

                    if(p==last)

                            last=temp;

            return last;

        }

    p=p->next;

} while(p!=last->next);

return last;

}




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