在循环链表的末尾插入节点的时间复杂度？

Question

Time complexity to insert a node at the end of circular singly linked list containing N elements ? Suppose I have pointer to the first node.

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I think that it is O(N) as I have to parse the LL to the node before the new node to modify its next field.

Have I got it right ?

Answer 1

Adding to the end of a circular singly linked list can be done in O(1) time.

1. Create a new node and insert it after your head node.
2. Copy your data from head into this new node.
3. Add your new data into the old head node.
4. Re-assign head.

As these are all constant time operations, this procedure is O(1).