LeetCode 203. Remove Linked List Elements Solution Explained - Java

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[researchandbuild]

Best explanation and the logic makes the most sense. Other videos i have found sucked at explaining this

[hassansmallah]

same here Failed for input: 1-> 2-> 2-> 1

i think it's a new test case. cheers

[Omniescience]

Why does saying “current_node.next = current_node.next.next” line 18 change the head linked list, but saying “current_node = current_node.next” line 20 does not? If changing current_node has an effect on the head, and current node is getting smaller as you traverse until you get to null. Maybe it’s just something I don’t understand about traversing linked list. This is a new data structure to me.

[FractalOut]

I don't understand why we are returning head, if we are changing values within current. Can someone please explain this to me?

[jayachandra]

I tried it many times without watching any of the solutions and then I came to this video and realized that I had to move the head pointer forward until the values are not equal before performing any other operations. Thank you!

[XAyaDubX]

This video helped me on an important assignment. Thank you very much!

[qusai]

what about the conditions ?
. it is strange that test case of "The number of nodes in the list is in the range [0, 104]." didn't appear after summation

[varshilanavadia]

If you interchange the conditions in the while loop, that is...

while(head.val != val && head != null) { // do something }

Leetcode throws a runtime exception for a test case when you submit the code.

Anyone know why ? Does it have to do with how conditions within the while loop are evaluated ? The conditions are the same, just the order is reversed, what's wrong with that ?

[shrirambalaji]

I initially solved the problem, but I ignored one possibility: what if head.value is value. Thank you for the answer, buddy.

[madanmohan]

while (head != NULL && head->val == val)
why can't we use here if instead of while?
and,
while (curr != NULL && curr->next != NULL)
why we have to check these both conditions?

[siuwan]

Hi, Nick! I have a question about why you need to return head at the end of the function?

[anmoljaising]

What's the need for lines 11-12? @nickwhite

[Rob-J-BJJ]

thanks i solved the problem i just didnt put it in an if else condition so i was getting adjacent elments wrong

[ankushchhabra]

thanks for explaining this solution so well
:)

[akankshakanjolia]

Thanks man!! it was very clean and easy approach

[Glam]

why do you define the current_node as another node and dont write just head?

[anirudhramprasad]

This program will not work for 2 consecutive values in a list which have the value val. Say in a list with values [2, 4, 4, 2] for example, if the current node carries the value 2, the program will remove the second node with the value 4 and current will take the next value of 4. Because of this the second value of 4 will not be checked against val leaving it in the list.

[smartswaggy]

Why this code doesnt work in C++

ListNode* removeElements(ListNode* head, int val) {
while(head!=NULL and head->val==val){
return head->next;
}
ListNode* current=head;
while(current!=NULL and current->next!=NULL){
if(current->next->val==val){

}
else{
current=current->next;
}

}
return head;
}

[chenchangyuan]

Thanks, but I got a problem that mine complexity is not good as yours well my code is the same as yours. XD

[ameytarfe]

Failed for input: 1-> 2-> 2-> 1