Week 12 Notes for CS 2500, Section 001 -- Spring 2002

• Look at Upcoming Schedule
• Class starts at 09:40. I take roll at 09:50
• Announcement(s)
  • I am handing back quiz #2
• Is everyone clear on what they have to do to implement the list class with a circular list?
• Discuss binary trees, tables, and binary search trees.
  • ADT binary tree
    • Finish up discussion started last week of how traversal works in binary trees. Do this by going over the code for

      virtual void PreorderTraverse(functionType Visit);

      (See file BT.cpp in the week11 notes section, or pp. 461, 462 of the Carrano text.)
      
      
    • Briefly Discuss the other binary tree operations (For a list of function prototypes for the operations, see the file BT.h in the week11 directory. See pp. 446-448 of the text for a set of specifications of all the operations.) We note what these operations are and what they do, but we do not need to spend much time in class considering them.
• Briefly discuss the ADT table -- see the specs in Carrano, Chapter 11, p. 529.
  • The table is important -- a basic data type for representing many kinds of databases.
  • We can use a simple array based list or linked list to implement a table, but neither of these implementations will be very efficient if the number of items to be stored is large. (Discuss)
  • The table ADT can be implemented quite efficiently as a binary search tree. This explains the importance of binary search trees.
  • Organization of the Table data type -- There is a totally ordered set of keys. Each element of the table contains a data field. Each element is also assigned a unique key. Elements and the data in them are accessed by key value.
  • Elements of a Table data type -- data fields from any homogeneos set -- typically each element of the table is a certain kind of record which may contain many different information fields -- an employee record for example.
  • Major Table data type Operations
    • Insert by key value
    • Delete by key value
    • Retrieve by key value
    • Traverse Table
• What is the reason for using BST's? -- they provide a hybrid of the array and linked list versions of a table in which all major operations can be implemented efficiently.
• ADT binary search tree
  • Organization -- A binary search tree is a binary tree in which each node contains a key that is an element of a totally ordered set. For every node N in the tree, all keys in the left subtree of N are less than the key in N, and all keys in the right subtree of N are greater than the key in N.
  • Elements -- any given homogeneous set
  • Operations -- see the file BST.h (week11 directory or p. 487 of Carrano) for the list and the specs. Discuss the following, just conceptually with diagrams (we will look at actual code next week.)
    • Discuss how binary search works in a BST.
    • Discuss implementation of retrieval.
    • Discuss implementation of insertion.
    • Discuss implementation of deletion.
      • -- when the delete node is a leaf
      • -- when the delete node has one child
      • -- when the delete node has two children

• Look at Upcoming Schedule
• Class starts at 09:40. I take roll at 09:50
• Announcement(s)