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    Question

    Which of the following operations is NOT valid for a

    circular linked list?
    A Traversing the list starting from any node. Correct Answer Incorrect Answer
    B Inserting a node at the beginning. Correct Answer Incorrect Answer
    C Deleting a node by value. Correct Answer Incorrect Answer
    D Traversing the list without a termination condition. Correct Answer Incorrect Answer
    E Sorting the list in-place using merge sort. Correct Answer Incorrect Answer

    Solution

    A circular linked list is a variation of a linked list where the last node points back to the first node, forming a loop. While this structure allows for continuous traversal from any node, it requires a termination condition to avoid infinite loops during traversal. Option 4, "Traversing the list without a termination condition," is invalid because the traversal would never end unless a condition (such as returning to the starting node) is used. Valid Operations: • Option 1 (Traversing from any node): Circular linked lists enable traversal from any node because the structure forms a loop. This is valid and often used in real-world applications like scheduling. • Option 2 (Inserting at the beginning): This is straightforward by updating the head pointer and linking the new node to the existing head. • Option 3 (Deleting a node by value): This involves finding the node to be deleted and updating the links of the surrounding nodes. It is more complex than insertion but valid. • Option 5 (Sorting using merge sort): Merge sort can be implemented in-place for linked lists, including circular ones, by breaking and reforming links. The lack of a termination condition (option 4) is fundamentally incompatible with the circular nature of the list. Without stopping at a specific condition, such as revisiting the start node, traversal would result in an infinite loop.

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