Java: Making a linked list in a while loop

Question

I am trying to make an int (like 123) into a linked list. For example: 123 would result in a linked list of 3 -> 2 -> 1. My issue is that I am able to get each part of the number(like 3 or 2) but I can't seem to make the linked list.

Here is my while Loop:

        value = Integer.parseInt(l1StrRev) + Integer.parseInt(l2StrRev);
        result = new ListNode(value % 10);
        value = value / 10;
        while(value > 0) {
            int newVal = value % 10;
            result.next = new ListNode(newVal);
            result = result.next;
            value = value / 10;
        }

I am getting back a linked-list of just one node with the most recent value.

Are you trying to use your own implementation of a LinkedList or use the one provided by java? — Nicholas K
– Nicholas K, Commented Oct 24, 2018 at 17:29
I am given a class: ListNode with int val, ListNode node, and a constructor — Toffe1369
– Toffe1369, Commented Oct 24, 2018 at 17:32

Rajarshi basu · Accepted Answer · 2018-10-24 17:34:06Z

2

In your code, you are updating the "result" variable too. So when u return the "result" variable, its actually pointing to the last Node. I would suggest, before the while loop do a resultCopy = result. And then in the end return resultCopy. This way, resultCopy stores the head node of the list, and "result" acts as a temporary node as in ur code.

answered Oct 24, 2018 at 17:34

Rajarshi basu

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1 Comment

Toffe1369 Over a year ago

Thank you so much!

elvaston5 · Accepted Answer · 2018-10-24 18:42:54Z

-1

Looks like you are missing and mixed up a couple of lines. In your loop it should be something like...

Create a new node

Node node = new ListNode(newVal);
Set node.next to the result

node.next = result;
Your result then becomes the new node above

result = node;

edited Oct 24, 2018 at 18:42

answered Oct 24, 2018 at 17:55

elvaston5

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