Insert Node at nth position in a linked list

linked list Interview Question

Insert Node at nth position in a linked list

You’re given the pointer to the head node of a linked list, an integer to add to the list & the position at which the integer must be inserted. Create a new node with the given integer, insert this node at the desired position and return the head node. A position of zero indicates head, a position of 1 indicates one node away from the head and so on. The head pointer given may be null meaning that the initial list is empty.

Input Format

You have to complete the Node Insert(Node* head, int data, int position) method which takes three arguments the head of the linked list, the integer to insert and the position at which the integer must be inserted. You should NOT read any input from stdin/console. position will always be between 0 and the number of the elements in the list.

Output Format
Insert the new node at the desired position and return the head of the updated linked list. Do NOT print anything to stdout/console.
Sample Input
NULL, data = 3, position = 0
3 --> NULL, data = 4, position = 0
Sample Output

3 --> NULL
4 --> 3 --> NULL
Explanation

1. we have an empty list and position 0. 3 becomes head.
2. 4 is added to position 0, hence 4 becomes head.

Node* InsertNth(Node *head, int data, int position)
{
  // Complete this method only
  // Do not write main function. 
    struct Node* newnode = (struct Node*)malloc(sizeof(struct Node*));
    newnode->data=data;
    newnode->next=NULL;
    struct Node*  ptr = head; 
    if(ptr==NULL)
        {
        head = newnode;
        return head;
    }
    else if(position==0)
        {
        newnode->next=head;
        head=newnode;
        return head;
    }
    else
        {
        while(position>1)
        {   
            ptr=ptr->next;
            position--;
        }
        if(ptr->next==NULL)
        {
            ptr>next=newnode;
        }
        else
        {
            newnode>next=ptr->next;
            ptr->next=newnode;
        }
        return head;
    }
}

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