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Code Circular Linked List

Check if a linked list is Circular Linked List

The problem involves checking whether a given singly linked list is a circular linked list or not. In a circular linked list, the last node's next pointer points back to the first node, creating a closed loop.

Problem Statement

Given a singly linked list, we need to determine whether it's a circular linked list or not.

Example

Consider the following linked list: 1 -> 2 -> 3 -> 4 -> 5. This is not a circular linked list because the last node's next pointer is NULL. However, if we connect the last node's next pointer to the first node, it becomes a circular linked list: 1 -> 2 -> 3 -> 4 -> 5 -> 1.

Idea to Solve the Problem

Length of Loop in linked listcheck linked list is circular or not

To check if a linked list is a circular linked list, we can traverse the list while checking if the next pointer of the current node ever becomes NULL. If we encounter a NULL next pointer, it means the list is not circular. If we encounter a node whose next pointer points back to a previously visited node, it indicates that the list is circular.

Pseudocode

Here's the pseudocode to check if a linked list is circular:

function isCircular(linkedList):
    if linkedList.head is NULL:
        return 0
    
    temp = linkedList.head
    while temp is not NULL:
        temp = temp.next
        if temp is linkedList.head:
            return 1
        if temp is NULL:
            return 0

Algorithm Explanation

  1. Check if the linked list is empty. If it's empty, return 0 (not circular).
  2. Initialize temp to the head of the linked list.
  3. Traverse the linked list using the temp pointer. If temp becomes equal to the head again, return 1 (circular).
  4. If temp becomes NULL, return 0 (not circular).

Code Solution

Time Complexity

The time complexity of checking whether a linked list is circular or not is O(n), where n is the number of nodes in the linked list. This is because we need to traverse the entire list to determine its circular nature.

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