Point of intersection of 2 linked lists

Given pointers to the heads of two linked lists. They intersect at some element, and proceed as a single list there-onwards. Find the point of intersection in O(n).


  1. one of the solution can be using two for loops and checking individual pointers at each node if they matches.

    Another solution can be by adding one more field in linked list of boolean type which will store information about whether that node is already visited.


  2. 1) Get count of the nodes in first list, let count be c1.
    2) Get count of the nodes in second list, let count be c2.
    3) Get the difference of counts d = abs(c1 – c2)
    4) Now traverse the bigger list from the first node till d nodes so that from here onwards both the lists have equal no of nodes.
    5) Then we can traverse both the lists in parallel till we come across a common node. (Note that getting a common node is done by comparing the address of the nodes)


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