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BJP5 Exercise 17.16: tighten

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Author: Robert Baxter (on 2019/09/19)

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.

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