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

completeToLevel

Related Links:
Author: Robert Baxter

Write a method completeToLevel that accepts an integer n as a parameter and that adds nodes to a tree so that the first n levels are complete. A level is complete if every possible node at that level is not null. We will use the convention that the overall root is at level 1, it's children are at level 2, and so on. You should preserve any existing nodes in the tree. Any new nodes added to the tree should have -1 as their data.

For example, if a variable called tree refers to the tree below at left and you make the call of tree.completeToLevel(3);, the variable tree should store the tree below at right after the call.

Before Call After Call 
            +----+
            | 17 |
            +----+
           /      \
          /        \
      +----+      +----+
      | 83 |      |  6 |
      +----+      +----+
     /                  \
    /                    \
+----+                  +----+
| 19 |                  | 87 |
+----+                  +----+
      \                /
       \              /
      +----+      +----+
      | 48 |      | 75 |
      +----+      +----+

                  +----+
                  | 17 |
                _ +----+ _
            _ /            \ _
          /                    \
      +----+                  +----+
      | 83 |                  |  6 |
      +----+                  +----+
     /      \                /      \
    /        \              /        \
+----+      +----+      +----+      +----+
| 19 |      | -1 |      | -1 |      | 87 |
+----+      +----+      +----+      +----+
      \                            /
       \                          /
      +----+                  +----+
      | 48 |                  | 75 |
      +----+                  +----+

In this case, the request was to fill in nodes as necessary to ensure that the first 3 levels are complete. There were two nodes missing at level 3, Notice that level 4 of this tree is not complete because the call requested that nodes be filled in to level 3 only.

Keep in mind that your method might need to fill in several different levels. Your method should throw an IllegalArgumentException if passed a value for level that is less than 1.

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.