## Thursday, June 9, 2016

### Check if a linked list is Circular Linked List - GeeksforGeeks

Given a singly linked list, find if the linked list is circular or not. A linked list is called circular if it not NULL terminated and all nodes are connected in the form of a cycle. Below is an example of circular linked list.

An empty linked list is considered as circular.
Note that this problem is different from cycle detection problem, here all nodes have to be part of cycle.

The idea is to store head of the linked list and traverse it. If we reach NULL, linked list is not circular. If reach head again, linked list is circular.
`bool` `isCircular(``struct` `Node *head)`
`{`
`    ``// An empty linked list is circular`
`    ``if` `(head == NULL)`
`       ``return` `true``;`

`    ``// Next of head`
`    ``struct` `Node *node = head->next;`

`    ``// This loop would stope in both cases (1) If`
`    ``// Circular (2) Not circular`
`    ``while` `(node != NULL && node != head)`
`       ``node = node->next;`

`    ``// If loop stopped because of circular`
`    ``// condition`
`    ``return` `(node == head);`
`}`