AVL Binary Tree for C++

• Download source and demo project - 194 Kb

Introduction

Very often, I had wanted a container that provides fast insertion and fast indexing. I also often had the need for sorted containers. Here, I present an AVL binary tree implementation that serves all these needs.

Background

• Here is some info on AVL binary trees: AVL Trees.
• Here is another CodeProject entry on AVL binary trees (I haven't used this implementation):

  Addison-Velski and Landis (AVL) Binary Trees.

• Here is a CodeProject entry discussing Chen Venkataraman's HighResElapsedTimer that I use in the example program:

  High Resolution Elapsed Timer.

Using the code

You can use the HeightBalancedTree<> template as either a sequence container that supports fast arbitrary insertions and deletions of objects, or as a sorted container.

If you use the tree as a fast sequence container, use the methods InsertByIndex, FindByIndex, and RemoveByIndex.

If you use the tree as a sorted container, use the methods InsertComparable, FindComparable, and RemoveComparable. These methods use the user-provided Comparator type to compare the objects stored inside the container.

You can always use the overloaded operator[] that works just like FindByIndex. It throws a std::out_of_range exception if the index is invalid.

All by-index modification and access methods of the container take approximately O(log(n)) time.

All by-comparison modification and access methods of the container take approximately O(k * log(n)) time, where k is the time taken to compare any two objects.

Here's some sample code that creates and modifies a random-access array of size_ts:

typedef HeightBalancedTree<size_t> SizeTTree;
SizeTTree tree;
for (size_t i = 0; i < n; ++i)
{
    tree.InsertByIndex(indices[i], data[i]);
}
for (size_t i = 0; i < n; ++i)
{
    tree.RemoveByIndex(0);
}

Here's some sample code that creates and modifies a sorted sequence of strings:

#ifdef UNICODE
    std::wostream & tcout = wcout;
    typedef HeightBalancedTree<
        std::basic_string<wchar_t>,
        StringComparator<
            std::basic_string<wchar_t>
        >
    > TStringTree;
#else
    std::ostream & tcout = cout;
    typedef HeightBalancedTree<
        std::string,
        StringComparator<std::string>
    > TStringTree;
#endif

TStringTree tree;
tree.InsertComparable(TEXT("ABE"));
tree.InsertComparable(TEXT("aBdE"));
tree.InsertComparable(TEXT("AbCd"));
tree.InsertComparable(TEXT("aBc"));
tree.InsertComparable(TEXT("AbD"));
tree.InsertComparable(TEXT("aBe"));
for (size_t i = 0; i < tree.Size(); ++i)
{
    tcout << "tree[" << i << "] = 
                  " << tree[i] << endl;
}

Points of Interest

Tell me what you think of this. I'm open to suggestions.

History

• 2005, December, 14 - 1.0.1 Fixed a bug in FindComparable: the returned index was wrong.
• 2005, December, 13 - Initial version uploaded to CodeProject.

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