Description
1 Introduction
Assignment 4 deals with binary search trees (BSTs). In this assignment,
you’ll create a program that lets a user enter data, and builds a BST from
that data. Your program will also let the user interact with that BST, using
a series of commands:
• s number – this will search for “number” in the BST. Tell the user
whether that number is found or not.
• d number – search for “number” and, if found, delete it. If it is not
found, tell the user.
• X – this command is used to display information about the BST. The
following information should be displayed:
– pre-, in- and post-order traversal of the tree. For each one, output the string “NLR” ”LNR:” or ”LRN:” followed by a commaseparated list of the nodes. Output one line for each traversal.
– output data from a breatdh-first traversal of the tree: Output the
string “BFS:” followed by a comma-separated list of the nodes.
– output the height of the tree (an empty tree has height -1; a tree
with a single node has height 0; etc.) Your output should say
“HEIGHT:” followed by the height.
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– Indicate whether or not the tree is balanced. Your output should
say “BALANCED:” followed by “YES” or “NO”
• ? – display a help message giving the user a list of valid commands.
• Q – exit the program
If only a number is entered (positive, negative, or 0), insert it into the tree.
Only allow a number to be entered once. If the user tries to insert a
number that’s already in the tree, you should print an error message and not
insert the second copy of the number.
Typing anything else should print an error message, and tell the user how to
get help.
2 Details
Do not balance the tree! Insert nodes only below leafs, in the unique location
that preserves the property of being a BST. When deleting a node N, select
the largest node from N’s left sub-tree to replace N, unless there is no left
sub-tree; in that case, move the root to point to N’s right sub-tree.
Be sure to free all memory that you allocate. Use valgrind on your code to
ensure there are no memory leaks.
Use your queue from PA3 for implementing breadth-first search (BFS).
You should code your insert, search, delete, height, balance-check and depthfirst-search routines recursively, as discussed in class. Your breadth-first
search should be implemented using a queue.
Create a makefile to build your executable image (which should be called
“pa4”). Bundle all your source files and your makefile into a single .tar and
upload via Canvas by the due date.
3 Suggestions
I suggest writing your insert and in-order traversal code first. This lets you
make a main program that simply calls your insert code with fixed values,
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which should build a tree. Then you can call your traversal code to confirm
that your insertion works correctly. Once that is working, deletion is the
next major hurdle.
Make your code modular, and use simpler pieces to help you in writing the
more complex parts of your code.
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