Deleting duplicate nodes in singly linked list in Javascript

Asked Oct 31 '16 at 07:22

Active Oct 31 '16 at 07:32

Viewed 38 times

I'm trying to delete duplicate nodes in a singly linked list: [1,1,2] would return [1,2].

So I would check if head.val == head.next, and if so, set head.val = null. However, in Javascript, null apparently returns an object. So now my output would be [[],1,2] instead of the desired [1,2].

var deleteDuplicates = function(head) {
    if (!!(head && head.next)) {
        if (head.val === head.next.val) {
            head.val = null;
        }
    }
    return head;
};

How can I get it to return [1,2]?

P.S. this is a coding question from Leetcode - I'm just wondering how I can set the value to nothing instead of null, which is an object.

edited Oct 31 '16 at 07:32

asked Oct 31 '16 at 07:22

patrickhuang94

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1

You need to show what you have tried so far. – Tibrogargan Oct 31 '16 at 07:26
@Tibrogargan it's been added. – patrickhuang94 Oct 31 '16 at 07:39
Is your linked list sorted? – Ivan Sivak Oct 31 '16 at 07:40
Yes, it's sorted. Please understand the scope of the question - all I'm asking is, how can I not return an object when I set it to null? – patrickhuang94 Oct 31 '16 at 07:41
change `head.val = null;` to `head.next = head.next.next;` – Tibrogargan Oct 31 '16 at 07:48
2

You don't want to be setting value to null, but setting the next to skip. `head.next = head.next.next` also your function is not iterative so would only delete one duplicate.. – Keith Oct 31 '16 at 07:51
@Keith, what happens when there is no head.next.next? In the case of [1,2,3,3], the first 3's `head.next.next` would be null. – patrickhuang94 Oct 31 '16 at 20:11
You would want it to be null.. ps. @Teemu this is NOT a duplicate of your link, a javascript array is not a single linked list, either un-mark this as a duplicate, or link to a question that does have single linked list in it that removes duplicates. – Keith Nov 01 '16 at 12:30

Deleting duplicate nodes in singly linked list in Javascript

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