How do you sketch a doubly linked list with a tail pointer?

To sketch a doubly linked list with a tail pointer, draw nodes connected by arrows in both directions and a tail pointer to the last node.

A doubly linked list is a type of data structure where each node contains a data part and two pointers. The first pointer points to the previous node in the list, and the second pointer points to the next node. A tail pointer in a doubly linked list is a special pointer that always points to the last node of the list.

To sketch this, start by drawing a series of rectangles (representing nodes) in a horizontal line. Each rectangle should be divided into three parts. The left part represents the pointer to the previous node, the middle part represents the data, and the right part represents the pointer to the next node.

Draw an arrow from the 'next' part of the first node to the 'previous' part of the second node, and vice versa. Repeat this process for all consecutive nodes in the list. This represents the double linkage of the list, where each node is connected to both its previous and next nodes.

The tail pointer is represented by a separate arrow coming from a point labelled 'tail'. This arrow should point to the last node in the list. This tail pointer is useful in many operations where we want to get to the end of the list quickly, such as appending a new element at the end of the list.

Remember, the first node (also known as the head node) in a doubly linked list has its 'previous' pointer pointing to null, indicating that it's the start of the list. Similarly, the last node (also known as the tail node) has its 'next' pointer pointing to null, indicating the end of the list.

In summary, a sketch of a doubly linked list with a tail pointer should show a series of nodes, each connected to its neighbours in both directions, with a separate tail pointer indicating the end of the list.