What are the two pointers used in the sorted insertion algorithm?

• A. current (to iterate) and trailCurrent (to track the node before current)
• B. head and tail
• C. previous and next
• D. fast and slow

Answer: (A)

Two pointers used in the sorted insertion are current and trailCurrent. The idea is to walk through the list with current, comparing values to find where the new node should go, while trailCurrent remembers the node just before current. This lets you splice in the new node by linking trailCurrent.next to the new node and newNode.next to current. If the new value should be at the head, trailCurrent is null, so you update the head to the new node and make its next point to the old head. If it goes at the end, current becomes null and trailCurrent.next points to the new node with its next set to null. This pair gives you the exact surrounding context needed to insert in one pass. Head and tail are just endpoints and don’t provide the adjacent-node context needed during traversal, and while previous and next describe a similar idea, the common approach in a singly linked list uses current and trailCurrent to track the node being examined and the node before it.