LinkedList/rotate_linked_list library

� Rotate Linked List — robust, generic implementation

Rotates a singly linked list to the right by k places and returns the new head. The function operates in-place (O(1) extra space) and runs in a single pass to compute length plus a second pass to rewire pointers when necessary.

Contract:

  • Inputs: head (nullable linked list head), k (non-negative rotation count).
  • Output: new head of the rotated list (nullable). Returns null when head is null.
  • Error modes: negative k is treated as invalid (caller should provide non-negative k).

Complexity: Time O(n), Space O(1).

Example:

final head = LinkedListNode.fromList([1,2,3,4,5]);
final rotated = rotateLinkedList(head, 2);
// rotated: [4,5,1,2,3]

Functions

rotateLinkedList<T>(LinkedListNode<T>? head, int k) → LinkedListNode<T>?