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geeksforgeeks.org/?p=2405

It can be done in this way
1. Find out the length of both lists.
2. Subtract small one from longer - This will bring both in same point to traverse
3. Now start traversing both & check for pointers. If they both are same at any point of time, they are intersecting. Else they are not

traverse the lists from head to tail and put the node pointers of each lists in stacks
ListA -> StackA
ListB -> StackB

(1) if they intersect, then the top element of both stacks will be same
(2) if (1) is true, keep popping up till the elements of stack have same value (node addresses) the last popped will be the intersection point
Eg- 100 is the last matched and popped node in the following
2--3--4--5--6--7--
\--- 100--200--300
20--30--40--50-- /

stackA 300--200--100--7--6-- ...--2
stackB 300--200--100--50--40--30--20

little unclear about question. are you asking 'intersection of two linked lists' or 'loop in a single list'?

I think it can be done as follows.
1) First linked list - Insert all the references in HashTable.
2) Second linked list - traverse list and check each node reference if present in HashTable if yes that's the intersection point.

This approach is fast but space required is more.

what do "flags" mean?

i didnt get the logic of the program.So please let me know or mail me the logic for this problem on my mail id.My mail id is sfsyedfaisal@gmail.com

Thanking you,
S.M.Faisal