Circular doubly linked list:

• In a circular doubly linked list, the last node’s "Next" pointer points to first node and "Prev" pointer of first node points to last node making the list circular from both of the directions.
• The "Next" of last link points to first link of list
• The "Prev" of first link points to last of list.
• A circular doubly linked list is shown below:

EBK DATA STRUCTURES AND ALGORITHMS IN C, Chapter 3, Problem 1E

Modification of linked list:

Refer figure 3.29 from chapter 3 for the given circular doubly linked list.

Assignment 1

• In the given list list->next denotes first element of list whose value is 1.
• In the given list list->next->next denotes second element of list whose value is 2.
• In the given list list->next->next->next denotes the third element of list whose value is 3
• In the given list list->prev denotes the last element of list whose value is 5, as the list is circular doubly linked list.
• Hence, assignment 1 would make the “Next” of node 3 to point to node 5. Hence, the result is “node 3 to node 5”.

Assignment 2

• In the given list list->prev denotes first element of list whose value is 1.
• In the given list list->prev->prev denotes last element of list whose value is 5.
• In the given list list->prev->prev->prev denotes the fourth element of list whose value is 4
• In the given list list->next denotes first element of list whose value is 1
• In the given list list->next->next denotes second element of list whose value is 2
• In the given list list->next->next->next denotes the third element of list whose value is 3
• In the given list list->next->next->next->prev denotes the “Prev” of fourth element of list
• Hence, assignment 2 would make node 4 point to node 4 itself. Hence, the result is “node 4 to node 4”.

Assignment 3

• In the given list list->next denotes first element of list whose value is 1.
• In the given list list->next->next denotes second element of list whose value is 2.
• In the given list list->next->next->next denotes the third element of list whose value is 3
• In the given list list->next->next->next->prev denotes the previous of fourth element of list
• In the given list list->prev denotes the last element of list whose value is 5, as list is circular linked list.
• In the given list list->prev->prev denotes the fourth element of list whose value is 4.
• In the given list list->prev->prev->prev denotes the previous of fourth element of list
• Hence, assignment 3 would denote same thing and list remains the same. Hence, the result is “No change”.

Assignment 4

• In the given list list->next denotes the first element of list whose value is 1.
• In the given list list->next->next denotes the third element of list whose value is 3.
• Hence, assignment 4 would make the node 1 point to node 3. Hence, the result is “node 1 to node 3”.

Assignment 5

• In the given list list->next denotes the first element of list whose value is 1.
• In the given list list->next->next denotes the second element of list whose value is 2.
• In the given list list->next->next->next denotes the “next” of second element of list whose value is 2.
• In the given list list->next denotes the second element of list whose value is 2.
• In the given list list->next ->prev->next denotes the first element of list whose value is 1.
• Hence, assignment 5 would make the “next” node 2 point to node 1. Hence, the result is “node 2 to node 1”.