Important Notice:

Practice-It will be discontinued as of November 1st, 2024. After this date, the website will remain online for a transitional period, but login will be restricted to University of Washington NetID authentication. This marks the next phase towards the platform's full retirement. Thank you for your use and support of the application over the years.

If you are looking for an alternative, a similar tool, CodeStepByStep, was developed independently by the original author of Practice-It, and is available at codestepbystep.com**

logo Practice-It logo

Main Page → Problems → Solve a Problem

BJP3 Exercise 17.16: tighten

Related Links:
Author: Robert Baxter (on 2013/04/01)

Write a method tighten that eliminates branch nodes that have only one child. For example, if a variable called tree stores the tree below at left, the call of tree.tighten(); should leave tree storing the tree at right:

Before Call After Call 
                    +---+
                    | 2 |
                ___ +---+ ___
              /               \
          +---+               +---+
          | 8 |               | 9 |
          +---+               +---+
         /                   /
     +---+               +---+
     | 7 |               | 6 |
     +---+               +---+
    /     \                   \
+---+     +---+               +---+
| 4 |     | 1 |               | 0 |
+---+     +---+               +---+
               \             /     \
               +---+     +---+     +---+
               | 3 |     | 4 |     | 5 |
               +---+     +---+     +---+

               +---+
               | 2 |
           ___ +---+ ___
         /               \
     +---+               +---+
     | 7 |               | 0 |
     +---+               +---+
    /     \             /     \
+---+     +---+     +---+     +---+
| 4 |     | 3 |     | 4 |     | 5 |
+---+     +---+     +---+     +---+

The nodes that stored the values 8, 9, 6, and 1 have been eliminated because each had one child. When a node is removed, it is replaced by its child. This can lead to multiple replacements because the child might itself be replaced (as in the case of 9 which is replaced by 6 which is replaced by 0).

Assume that you are adding this method to the IntTree class as defined below: 

public class IntTree {
    private IntTreeNode overallRoot;
    ...
}
Type your solution here:


This is a partial class problem. Submit code that will become part of an existing Java class as described. You do not need to write the complete class, just the portion described in the problem.

You must log in before you can solve this problem.


Log In

If you do not understand how to solve a problem or why your solution doesn't work, please contact your TA or instructor.
If something seems wrong with the site (errors, slow performance, incorrect problems/tests, etc.), please

Is there a problem? Contact a site administrator.