Assignment Description

In this lab we’ll practice AVL tree rotations and insertions, and see some silly test cases.

Checking Out The Code

As usual, just run

svn up

from your cs225 directory. This will create a new folder in your working directory called lab_avl.

As usual, check out the Doxygen for lab_avl.

Implement Rotation Functions

You must implement rotateLeft(), rotateRight(), and rotateRightLeft(). We have implemented rotateLeftRight() for you as an example for implementing rotateRightLeft().

Implement the rebalance() Function

You must implement rebalance() function. rebalance() should, given a subtree, rotate the subtree so that it is balanced. You should assume that the subtree’s left and right children are both already balanced trees. The node’s height should always be updated, even if no rotations are required.

Implement the insert() Function

You must implement the insert() function. insert() should add a node with a key and value at the correct location in the tree, then rebalance appropriately (while returning from each recursive function) to fix the tree’s balance.

Implement the remove() Function

You must implement the remove() function. remove() should remove the node with the specified key from the tree, then rebalance appropriately (while returning from each recursive function) to fix the tree’s balance. You can assume that the key exists in the tree. You may want to use the swap() method.

To match the provided output (and grading scripts), you should use IOP (in order predecessor) for removing a node with 2 children.

Testing Your Code

To test your code, compile using make:


Then run it with:

./testavl color

You will see that the output is colored — green means correct output, red means incorrect output, and underlined red means expected output that was not present. This mode is a bit experimental, and it might cause problems with your own debugging output (or other problems in general). To turn it off, simply leave off the “color” argument:


You may also diff your solution with our expected output:

./testavl | diff -u - soln_testavl.out

Type [Escape] [:] [q] [a] [ENTER] to exit vimdiff.

Committing Your Code

Commit your code the usual way:

svn ci -m "lab_avl submission"

Grading Information:

The following files are used in grading:

All other files including any testing files you have added will not be used for grading.