Reverse a Singly Linked List In Place

Reverse a singly linked list and return its new head. ### Constraints and Clarifications For the standard practice contract, the list is finite and acyclic, each node has a value and a next reference, and an empty list is represented by a null head. Reverse links in place while preserving node values and identities. These structural assumptions make the named reversal task precise; no numerical size or value bounds were reported. ### What a Strong Answer Covers Save the next node before changing a link, maintain a reversed prefix and an unprocessed suffix, and explain the new tail and head. Compare iterative auxiliary space with a recursive approach. ### Follow-up Questions - What goes wrong if current.next is overwritten before saving the old next reference? - How would a cycle in the input affect the termination argument?