Finding loop in a singly linked-list

Question

How can I detect that whether a singly linked-list has loop or not?? If it has loop then how to find the point of origination of the loop i.e. the node from which the loop

Answer 1

Another solution

Detecting a Loop:

1. create a list
2. loop through the linkedlist and keep on adding the node to the list.
3. If the Node is already present in the List, we have a loop.

Removal of loop:

1. In the Step#2 above, while loop through the linked list we are also keep track of the previous node.

2. Once we detect the loop in Step#3, set previous node's next value to NULL

   #code

   def detect_remove_loop(head)

       cur_node = head
       node_list = []
   
       while cur_node.next is not None:
           prev_node = cur_node
           cur_node = cur_node.next
           if cur_node not in node_list:
               node_list.append(cur_node)
           else:
               print('Loop Detected')
               prev_node.next = None
               return
   
       print('No Loop detected')