datastructures/binary-trees/binarytree.hpp

#include <memory>

namespace BinaryTree
{
template <class T>
struct Node
{
	Node *parent;

	T value;

	std::unique_ptr<Node<T>> left;
	std::unique_ptr<Node<T>> right;

	bool IsLeaf() const
	{
		return left == nullptr && right == nullptr;
	}

	Node(T const &_value, Node<T> *_parent)
			: parent(_parent),
				value(_value)
	{
	}
};

template <class T>
class Tree
{
private:
	std::unique_ptr<Node<T>> root;

	std::unique_ptr<Node<T>> & GetRightMostLeaf(std::unique_ptr<Node<T>> &localRoot)
	{
		std::unique_ptr<Node<T>> *nodePtr = &localRoot;
		while ((*nodePtr)->right != nullptr)
		{
			nodePtr = &((*nodePtr)->right);
		}

		return *nodePtr;
	}

public:
	void Insert(T value)
	{
		Node<T> *previousPtr = nullptr;
		std::unique_ptr<Node<T>> *rootPtr = &root;
		while (*rootPtr != nullptr)
		{
			previousPtr = rootPtr->get();
			if ((*rootPtr)->value > value)
			{
				rootPtr = &((*rootPtr)->left);
			}
			else
			{
				rootPtr = &((*rootPtr)->right);
			}
		}
		*rootPtr = std::make_unique<Node<T>>(value, previousPtr);
	}

	bool Contains(T const value)
	{
		std::unique_ptr<Node<T>> *rootPtr = &root;
		while (*rootPtr != nullptr)
		{
			if ((*rootPtr)->value == value)
			{
				return true;
			}

			if ((*rootPtr)->value > value)
			{
				rootPtr = &((*rootPtr)->left);
			}
			else
			{
				rootPtr = &((*rootPtr)->right);
			}
		}

		return false;
	}

	void Delete(T const value)
	{
		std::unique_ptr<Node<T>> *rootPtr = &root;
		while (*rootPtr != nullptr)
		{
			if ((*rootPtr)->value == value)
			{
				if ((*rootPtr)->IsLeaf())
				{
					rootPtr->release();
					return;
				}

				if ((*rootPtr)->left == nullptr)
				{
					rootPtr->swap((*rootPtr)->right);
					(*rootPtr)->right.release();
				}
				else if ((*rootPtr)->right == nullptr)
				{
					rootPtr->swap((*rootPtr)->left);
					(*rootPtr)->left.release();
				}
				else
				{
					auto &replacementNode = GetRightMostLeaf((*rootPtr)->left);
					rootPtr->swap(replacementNode);
					replacementNode.release();
				}

				return;
			}

			if ((*rootPtr)->value > value)
			{
				rootPtr = &((*rootPtr)->left);
			}
			else
			{
				rootPtr = &((*rootPtr)->right);
			}
		}
	}
};
} // namespace BinaryTree