What is the algorithm for sorted insertion in an ordered linked list?

• A. Find the correct position for the new item based on its value and insert it there.
• B. Always insert at the head to maintain order.
• C. Always insert at the tail to maintain order.
• D. Swap the new item with the next item until it fits.

Answer: (A)

Maintaining a sorted linked list means placing the new element in the exact spot where all nodes before it are less than or equal to its value and all nodes after it are greater than or equal to it. To do this, start at the head and compare the new value with each node’s value, moving forward until you find a node whose value is greater than or equal to the new value. Insert the new node right before that node. If you reach the end, append the new node at the tail. This preserves the nondecreasing order after insertion. Edge cases, like an empty list, are handled by making the new node the head. The reason this approach is correct is that it updates the list’s pointers to link the new element into the exact position where the order property would be violated otherwise, ensuring the entire list stays sorted. Inserting at the head or at the tail without regard to the new value can break the order, and swapping elements doesn’t properly adjust the list’s links.