LeetCode Merge Two Sorted Lists Solution Explained - Java

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[stevothebeavo]

For anyone wondering, a linked list is a pointer data structure. This means that when we say “node.next = l1” it is a reference to a pointer which holds the full data. As such the old “next” pointer remains as well as the value. So at the very end we are truly appending the “rest” of the non null list not just a value without a next pointer (it so happens that lines 31&36 are useless)

[siddhantsingh]

Those who are submitting for the first time and getting an extra 0 in front of the list, its because you are returning the address of an empty node, whereas the first element is being stored in the next node to the head node. Try returning temp_node->next

[theducksneezes]

3:45 "First try!"
sees attempts. :o

On a serious note, this is really helpful. Thank you so much for posting this, please keep it up!

[headyshotta]

Im a third year CS student and even the easy leetcode problems make no sense to me usually. I can tell I still don't have that fundamental base yet. There is a certain level of assumed knowledge this video is going with. Oh well, I will get there : _ )

[jeffery]

awesome video. One issue though is on line #31 l1=l1.next and #36 l2=l2.next seems unnecessary

[vruttantbalde]

I wish i could see more of the editor rather than your face.

[akware]

thanks, nick for posting this, one suggestion front camera screen is blocking the end part of the code.

[GameFlife]

nick is so legend even my sister know him whenever she swing by my pc she's like hey thats NICK WHITE

[rezayegane]

Hi. I know about reference types (in Java or C#) but I don't understand how `head` get its value. what topics should I read about to know how its works?

[e.g.]

Would be much nicer if your photo wasn't covering up the code :(

[sankalppatil]

What if after one of the lists reaches null, the other list has more than one node left in it? For example if the lists were [1, 2, 3, 4] and [5, 6, 7, 8] by the time the first node reaches null the second list would still have 4 more nodes to go through since all the values were larger than the larger value in the first list. With the if statements he added at the end, his program would just pull the first node off the second list and possibly leave more remaining. Wouldn't you want to implement a while loop to go through the remaining list until it reaches null?

[davidfield]

Nick, it's a very good explanation, but your face covers part of the code.

[divyabharti]

Why we are just appending one last node in the final. What if we have 2 link list with 3 and 5 nodes. After while loop we need to append 2 items in the the final list from l2.

[SombaKalen]

How is temp_node being updated as curr updates during the traversal?

[jasmeenkaur]

why we return temp_node insteadof curr ???? why???

[abiramivadivel]

Very great ! Could you please explain the l1!=null part please I dont get why we really use it?

[pratikwadekar]

I was trying this problem by sorting inplace. Without creating new list. Was stuck for so many hours 😅

[vickyk]

I don't understand why you wrote the line 26 code.

[ashutoshwalimbe]

Shouldn't it be, l1.val <= l2.val ??

[lostmeme]

I was told on the interview that I cannot create a new list and this problem got me stumped.