Lab 20: Circular Doubly Sorted Linked List

Lab 20 Linked List Variation Circular Doubly Sorted Linked List Wi

This program reads a series of alphabetic items from a data file and inserts each item into a circular doubly linked list in sorted (ascending) order. The list contains a dummy head node to simplify insertion and deletion operations. The implementation involves constructing the list dynamically from data read from the file, displaying the list's contents after all insertions, and then destroying the list to free memory.

Paper For Above instruction

Implement a client program in C++ that models a circular doubly linked list with a dummy head node, maintaining the list in sorted order based on string data. The program should perform three main tasks: reading data from a file and constructing the list, displaying the contents of the list, and destroying the list to free memory.

Introduction

The circular doubly linked list with a dummy head node offers significant advantages for list manipulation, notably simplifying insertion and deletion by eliminating special cases at the beginning or end of the list. This design ensures that all nodes, including the dummy head, form a circular structure where the dummy’s next points to the first data node (or itself if empty), and the dummy’s precede points to the last data node. This structure supports maintaining data in sorted order, which is efficient for search, insertion, and deletion operations in sorted collections.

Core Components and Functions

The program will define four core functions:

  1. BuildSortedList: Reads the data file item by item, inserting each string into the list in sorted order using SortedListInsert.
  2. SortedListInsert: Accepts a list head pointer and a new data string; it traverses the list to find the correct insertion point and inserts the new node in sorted order.
  3. DisplayList: Traverses the list starting from the node after the dummy head and displays all data nodes sequentially.
  4. DestroyList: Frees all nodes in the list to prevent memory leaks, including the dummy head.

Implementation Details

The program begins with including standard headers and defining basic data types—specifically, ListItemType as string. The Node structure contains pointers to the previous and next nodes, along with a field for the data. With the dummy head node initialized to point to itself, the list starts empty.

Main Program Flow

  1. Open the data file "produce.dat" and check for successful opening.
  2. Construct the list by calling BuildSortedList. This reads each item line by line and inserts it into the list in sorted order.
  3. Display the list's contents to the user using DisplayList.
  4. Finally, call DestroyList to free allocated memory.

Function Definitions

BuildSortedList

This function reads data until EOF, and for each item, calls SortedListInsert for insertion. It handles file I/O robustly, ensuring each item is processed correctly.

SortedListInsert

The insertion function creates a new node with the data, then traverses the list starting from the dummy head's next. It locates the first node with data greater than the new item, and inserts the new node before it, updating the prev and next pointers accordingly. If no greater node is found, insertion occurs at the end just before the dummy head.

DisplayList

Uses a traversal loop starting from the node after dummy head, printing each data item until returning to the dummy head, thereby displaying all list elements in sorted order.

DestroyList

Iterates through the list starting at the node after dummy head, deleting each node one by one until only the dummy head remains, which is then also deleted.

Conclusion

This implementation enables efficient, sorted insertion into a circular doubly linked list with minimal special-case handling by leveraging the dummy head structure. Proper management of pointers during insertion and deletion ensures the integrity of the list, while the design facilitates easy traversal and memory management. Such data structures are fundamental in applications requiring dynamically maintained sorted collections, such as databases, priority queues, and event scheduling systems.

References

  • Weiss, M. A. (2014). Data Structures and Algorithm Analysis in C++ (4th ed.). Pearson Education.
  • Goodrich, M. T., Tamassia, R., & Goldwasser, M. H. (2014). Data Structures and Algorithms in C++ (2nd ed.). Wiley.
  • Skiena, S. S. (2008). The Algorithm Design Manual (2nd ed.). Springer.
  • Langr, D. (2012). Algorithms. O'Reilly Media.
  • Cormen, T. H., Leiserson, C. E., Rivest, R. L., & Stein, C. (2009). Introduction to Algorithms (3rd ed.). MIT Press.
  • Knuth, D. E. (1998). The Art of Computer Programming, Volume 3: Sorting and Searching. Addison-Wesley.
  • Sedgewick, R., & Wayne, K. (2011). Algorithms (4th ed.). Addison-Wesley.
  • Dasgupta, S., Papadimitriou, C., & Vazirani, U. (2008). Algorithms. McGraw-Hill.
  • Levitin, Anany. (2012). Introduction to the Design & Analysis of Algorithms. Pearson.
  • Martín, F. M. (2010). Efficient Data Structures. Springer.

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