Remove Nth Node from End of List - Leetcode 19 - Linked Lists (Python)

[@GregHogg]

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[@sajinreyans3329]

The behind and ahead that u just used 1.why did you use it 2. Can I use this algorithm anywhere else 3. Does this algorithm have any other name

[@yvettcodes]

@@sajinreyans3329 He used the behind and ahead variable as a way to set up a gap between the nodes at the correct distance. Notice how once he adjusted the Ahead variable in the initial for loop, he then moved both ahead and behind until ahead reached the very end of the linked list (ahead = None). If you count the distance between Ahead and Behind after he's corrected their positions, you'll notice that it is now n+1- ensuring that B is in the correct position for our goal of deleting a target node. Hope this helps!

[@zhihangcheng1083]

Elegent explaination!

[@kubs1162]

made way more sense to me when i though of it as l, r instead of ahead, behind

[@yvettcodes]

I solved this problem differently, but I love your solution more! Thanks for the explanation. If you ever read this, could you please make a video for 1721. Swapping Nodes in a Linked List? Thanks a bunch, Greg!

[@akshatsingh9830]

which sheet or roadmap are u following

[@yvettcodes]

@@akshatsingh9830 I'm not following anyone's specific roadmap, I am following Codecademy's DSA course to learn about the topic, then trying to do at least 8-10 problems for each of varying difficulty. Greg actually has a roadmap for leetcode problems though, and I plan to prioritize those questions and Blind/Grind75 questions for each topic as I learn.

[@habeebah6135]

Hello, does the while loop get added as o(m+n). Why not? Worst case scenario it could go n-1 times right if the n value is 1. I do not understand why it is just o(m) here. Thank you

[@mmm-ie5ws]

how does changing the behind variable change the summy variable?

[@yvettcodes]

What do you mean? The behind variable does not change the dummy variable in this scenario. Behind is only a pointer that enables us to access the correct nodes for deleting our target node.

[@harshapavanteja58]

hi