Flattening a linked list

pls explain me this question and how to approach this
https://practice.geeksforgeeks.org/problems/flattening-a-linked-list/1


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I already have seen this video and than asked thid doubt

If possible pls tell me the exact steps… I understood the problem by ur image

if u have 5 down lists let say 1,2,3,4,5
then merge 4th nd 5th to 4’
so resultant list 1,2,3,4’
then merge 3th nd 4’th to 3’
so resultant list 1,2,3’
then merge 2th nd 3’th to 2’
so resultant list 1,2’
then merge 1th nd 2’th to 1’
so resultant list 1’
you can see the code:

thanks :slight_smile: