Check if two linked lists merge. If so, where?

Question

This question may be old, but I couldn\'t think of an answer.

Say, there are two lists of different lengths, merging at a point; how do we know wher

Answer 1

There can be a simple solution but will require an auxilary space. The idea is to traverse a list and store each address in a hash map, now traverse the other list and match if the address lies in the hash map or not. Each list is traversed only once. There's no modification to any list. Length is still unknown. Auxiliary space used: O(n) where 'n' is the length of first list traversed.