check circular LL

Author: sachuverma

DSA Crack Sheet/README.md

@@ -138,6 +138,7 @@
 - [Middle of the Linked List](https://leetcode.com/problems/middle-of-the-linked-list/ "view question") - [Cpp Solution](./solutions/Middle%20of%20the%20Linked%20List.cpp)
 - [Merge Sort for Linked List](https://practice.geeksforgeeks.org/problems/sort-a-linked-list/1# "view question") - [Cpp Solution](./solutions/Merge%20Sort%20for%20Linked%20List.cpp)
 - [Quick Sort on Linked List](https://practice.geeksforgeeks.org/problems/quick-sort-on-linked-list/1# "view question") - [Cpp Solution](./solutions/Quick%20Sort%20on%20Linked%20List.cpp)
+- [Check If Circular Linked List](https://practice.geeksforgeeks.org/problems/circular-linked-list/1# "view question") - [Cpp Solution](./solutions/Check%20If%20Circular%20Linked%20List.cpp)
 - []( "view question") - [Cpp Solution](./solutions/.cpp)
 
 ### Binary Tree

DSA Crack Sheet/solutions/Check If Circular Linked List.cpp

@@ -0,0 +1,38 @@
+/*
+Check If Circular Linked List
+=============================
+
+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. An empty linked list is considered as circular.
+
+Example 1:
+Input:
+LinkedList: 1->2->3->4->5
+(the first and last node is connected,
+i.e. 5 --> 1)
+Output: 1
+
+Example 2:
+Input:
+LinkedList: 2->4->6->7->5->1
+Output: 0
+Your Task:
+The task is to complete the function isCircular() which checks if the given linked list is circular or not. It should return true or false accordingly. (the driver code prints 1 if the returned values is true, otherwise 0)
+
+Expected Time Complexity: O(N).
+Expected Auxiliary Space: O(1).
+
+Constraints:
+1 <=Number of nodes<= 100
+*/
+
+bool isCircular(Node *head)
+{
+  auto temp = head;
+  while (temp)
+  {
+    temp = temp->next;
+    if (temp == head)
+      return true;
+  }
+  return false;
+}