Insert a node at a specific position in a linked list JAVA

Question

public static SinglyLinkedListNode insertNodeAtPosition(SinglyLinkedListNode llist, int data, int position) {
    if(llist == null) {
        llist =  new SinglyLinkedListNode(data);
        return llist;
    } else {
        for (int i = 0; i < position-1; i++) {
            llist = llist.next;
        }
        SinglyLinkedListNode temp = llist;
        llist.next = new SinglyLinkedListNode(data);
        llist = llist.next;
        llist.next = temp.next;         
        return llist;
    }
}

This is my code to place a custom index node in LinkedList. But hackerrank is not accepting my code. What's wrong with my algorithm?

Answer 1

The problem is that your code always returns the newly created node, but you should always return the first<\/em> node in the list, which either is what it was when you got it, or is the new node in case the position was zero.

<\/h3>

I'll not provide the corrected code, but will give you two hints:

Answer 2

Easiest solution No need of explaination : Solution :

static SinglyLinkedListNode insertNodeAtPosition(SinglyLinkedListNode head, int data, int position) {
        if (head == null) return null;
        SinglyLinkedListNode temp = new SinglyLinkedListNode(data);
        if (position == 0) {
            temp.next = head;
            return temp;
        }
        SinglyLinkedListNode p = head;
        for (int i = 0; i< position-1; i++) {
            p = p.next;
        }
        SinglyLinkedListNode next = p.next;
        p.next = temp;
        temp.next = next;
        return head;
    }