The video begins with a greeting and an introduction to the 'Copy List with Random Pointer' coding challenge.

• The presenter greets the audience and expresses intent to write neat code.
• Introduces the problem and provides a brief overview of the linked list structure with a random pointer in each node.

The structure of the linked list in the problem is explained, highlighting the next and random pointers in each node.

• Describes the linked list as singly linked with an additional random pointer in each node.
• Random pointers can point to any node in the list or to null.
• The task is to create a deep copy of this linked list.

The concept of deep copying the linked list is introduced, which involves creating new nodes and setting the correct pointers.

• Each node in the list must be replicated with new memory allocation.
• A deep copy requires duplication of nodes as well as accurate replication of the next and random pointers.

The presenter outlines a two-pass algorithm for solving the problem and introduces the use of a hashmap.

• The first pass involves cloning nodes and creating a hashmap mapping original nodes to their copies.
• The second pass connects the next and random pointers using the hashmap.
• The hashmap allows for efficient assignment of the random pointer even before all nodes have been cloned.

The presenter discusses the creation of a hashmap that maps each original node to its copy.

• During the first pass, each original node is cloned and added to the hashmap.
• The hashmap is used to associate each original node with its corresponding copy.

The video explains how the second pass of the algorithm connects the pointers using the previously created hashmap.

• The second pass sets the next and random pointers for each copy node.
• The hashmap is leveraged to find and set the correct pointers for each new node.

The presenter walks through the code implementation of the two-pass algorithm step by step.

• Initiates a hashmap called 'old to copy' to map original nodes to their copies.
• Iterates through the list to clone nodes and populate the hashmap.
• Iterates a second time to set the next and random pointers for each cloned node using the hashmap.

The presenter describes how to return the head of the copied linked list using the hashmap.

• Accesses the copy of the head node from the hashmap.
• Returns the head of the copied list to complete the deep copy process.