CareerCup

@loop in linked list
------------------
take 2 pointers p,q
p=q=head;
do
p=p->next->next;
q=q->next;
while p!=q or p!=null
if p==q
loop exists
else
no loop

the faster pointer p meets q if there is a loop

Another way of doing it would be to use a hashmap.
Iterate through every node in the linked list:
Check if the address of node already exists in the hashmap?
If it does, then there is a loop.
Else
If it does not exist, put the address of the nodein the hashmap.

Data Structures I remember
- Primitive DS
- Array
- Stack
- Queue
- Heap
- Binary Tree
- Multiway tree
- Hash Table
- Map
- Multiset
- Bitmap
- Suffix tree
- Adjacency List
- Adjacency matrix
- Skip list
- Deque

Great solution to the loop detection, Ishwar4frendz. Thanks!