Clone Linked List with Random Pointer in DSA C - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a 'random pointer' in a linked list?

A random pointer is an extra pointer in each node of a linked list that can point to any node in the list or NULL, not just the next node.

intermediate

Why do we need to clone a linked list with random pointers carefully?

Because each node has a random pointer that can point anywhere, we must copy both the next and random pointers correctly to keep the structure intact.

intermediate

What is the first step in the common approach to clone a linked list with random pointers?

Insert a new cloned node right after each original node in the list, so the list looks like: original1 -> clone1 -> original2 -> clone2 -> ...

advanced

How do we set the random pointers of cloned nodes in the interleaved list?

For each original node, set the cloned node's random pointer to original node's random pointer's next node (which is the clone of the random target).

advanced

How do we separate the cloned list from the original after cloning?

We restore the original list by skipping cloned nodes and build the cloned list by linking cloned nodes together, effectively splitting the interleaved list into two.

What does the random pointer in a linked list node point to?

A Only the next node

B Any node in the list or NULL

C Only the previous node

D The head of the list

The random pointer can point to any node in the list or be NULL.

In the cloning process, why do we insert cloned nodes between original nodes?

A To reverse the list

B To sort the list

C To delete original nodes later

D To easily set random pointers of clones using original nodes

Inserting clones between originals helps set random pointers by using the next pointers of original nodes.

How do we assign the random pointer of a cloned node?

A clone->random = original->random->next

B clone->random = original->next

C clone->random = NULL

D clone->random = original

Because the clone of the random target is right after the original random target node.

What is the final step after setting next and random pointers in cloning?

A Delete the original list

B Reverse the cloned list

C Separate the cloned list from the original list

D Sort the cloned list

We separate the interleaved list into original and cloned lists.

What is the time complexity of cloning a linked list with random pointers using the interleaving method?

A O(n)

B O(n^2)

C O(log n)

D O(1)

The method visits each node a constant number of times, so it runs in linear time.

Explain the three main steps to clone a linked list with random pointers using the interleaving method.

Think about how to keep track of clones and originals together.

Why can't we simply copy nodes and random pointers in one pass when cloning a linked list with random pointers?

Consider what happens if random points forward or backward.