Question

I have a Linked List and I want to implement a function:

Random_Shuffle_List (struct node **Headptr) – which outputs a list such that every single node is randomly moved from its original position.

Please help me with an efficient algorithm to achieve this.

Answer 1

I would recommend the naïve approach:

1. Build a pointer array pointing at each node.
2. Shuffle the array. This is way, way easier than randomizing a linked structure.
3. “Re-thread” the list by stepping through the nodes in the array’s order.

This uses a relatively tiny bit of extra memory, of course, but I think it’s more “efficient” in terms of time to implement (and understand) and probably also run-time, than approaches working directly on the linked list.