c++模板类实现基础二叉树的各种操作

#include <vector>
#include <queue>
#include <stack>

template<class T>
struct BinaryTreeNode
{
    T _data;
    BinaryTreeNode<T>* _left;
    BinaryTreeNode<T>* _right;

    BinaryTreeNode(const T& x)
        : _data(x)
        , _left(NULL)
        ,_right(NULL)
    {}
};


template<class T>
class BinaryTree
{
    typedef BinaryTreeNode<T> Node;
public:
    BinaryTree(T *a, size_t n, const T& invalid)
    {
        size_t index = 0;
        _root = _CreateTree(a, n, invalid, index);
    }

    Node CopyTree(Node* root)
    {
        if (root == NULL)
            return NULL;
        Node* newRoot = new Node(root->_data);
        newRoot->_left = CopyTree(root->_left);
        newRoot->_right = CopyTree(root->_right);

        return newRoot;
    }

    BinaryTree(const BinaryTree<T>& t)
    {
        _root = CopyTree(t._root);
    }

    BinaryTree operator=(BinaryTree<T> t)
    {
        swap(_root, t._root);

        return *this;
    }

    ~BinaryTree()
    {
        Destory(_root);
        _root = NULL;
    }

    void Destory(Node* root)
    {
        if (root == NULL)
            return;
        Destory(root->_left);
        Destory(root->_right);
        delete root;
    }

    //前序遍历建树
    Node* _CreateTree(T* a, size_t n, const T& invalid, size_t& index)
    {
        Node* root = NULL;
        if (a[index] != invalid)
        {
            root = new Node(a[index]);
            root->_left = _CreateTree(a, n, invalid, ++index);
            root->_right = _CreateTree(a, n, invalid, ++index);
        }
        return root;
    }

    /*Node* _CirculeCreateTree(T* a, size_t n, const T& invalid, size_t index)
    {
        Node* root = NULL;

        while (a[index] != invalid)
        {
            root = new Node(a[index]);

            root->_left = root;
            index++;
        }
        index++;
    }*/

    //前序遍历访问树

    void PrevOrder()
    {
        _PrevOrder(_root);
        cout << endl;
    }

    void _PrevOrder(Node* root)
    {
        if (root == NULL)
            return;

        cout << root->_data << " ";
        _PrevOrder(root->_left);
        _PrevOrder(root->_right);
    }

    //中序遍历访问树

    void InOrder()
    {
        _InOrder(_root);
        cout << endl;
    }

    void _InOrder(Node* root)
    {
        if (root == NULL)
            return;
        _InOrder(root->_left);
        cout << root->_data << " ";
        _InOrder(root->_right);
    }

    void PostOrder()
    {
        _PostOrder(_root);
        cout << endl;
    }

    void _PostOrder(Node* root)
    {
        if (root == NULL)
            return;

        _PostOrder(root->_left);
        _PostOrder(root->_right);

        cout << root->_data << " ";

    }
//递归实现求二叉树的大小
    int Size()
    {
        size_t size = 0;
        Size(_root, size);
        return size;
    }


    void _Size(Node* root, size_t& size)
    {
        if (root == NULL)
            return;
        _Size(root->_left, size);
        ++size;
        _Size(root->_right,size);
    }
//求所有叶子节点的数量
    size_t LeafSize()
    {
        return _LeafSize(_root);
    }

    size_t _LeafSize(Node* root)
    {
        if (root == NULL)
            return 0;
        if (root->_left == NULL && root->_right == NULL)
            return 1;
        return _LeafSize(root->_left) + _LeafSize(root->_right);

    }
    //求树的高度
    size_t Height()
    {
        return _Height(_root);
    }

    size_t _Height(Node* root)
    {
        if (root == NULL)
            return 0;

        size_t leftHeight = _Height(root->_left);
        size_t rightHeight = _Height(root->_right);

        return leftHeight > rightHeight ? leftHeight + 1 : rightHeight + 1;

    }

    //获取第K层的节点数
    size_t GetKLevel(size_t k)
    {

        size_t Num = _GetKLevel(_root, k);
        cout << Num << endl;
        return Num;
    }

    size_t _GetKLevel(Node* root, size_t k)
    {
        if (root == NULL)
            return 0;
        if (k == 1)
            return 1;
        return _GetKLevel(root->_left, k - 1) + _GetKLevel(root->_right, k - 1);
    }

    //判断是不是完全二叉树
    bool IsCompleteTree()
    {
        queue<Node*> q;

        if (_root)
            q.push(_root);
        bool flag = true;

        while (!q.empty())
        {
            Node* front = q.front();
            q.pop();
            if (front->_left)
            {
                if (flag == false)
                    return flag;
                q.push(front->_left);
            }
            else
            {
                flag == false;
            }
            if (front->_right)
            {
                if (flag == false)
                    return flag;
                q.push(front->_right);
            }
            else
            {
                flag = false;
            }
        }
        return true;
    }
//查找指定的节点
    Node* Find(const T& x)
    {
        return _Find(_root, x);
    }

    Node* _Find(Node* root, const T& x)
    {
        if (root == NULL)
            return NULL;
        if (root->_data == x)
            return root;

        Node* cur = _Find(root->_left, x);
        if (cur)
            return cur;
        Node* tem = _Find(root->_right, x);
        if (tem)
            return tem;
    }

private:
    Node* _root;
};



void TestTree()
{
    int array[] = { 1, 2, 3, '#', '#', 4, 40, '#', '#', '#', 5, 6, '#', '#', '#' };
    BinaryTree<int> t(array, sizeof(array) / sizeof(int), '#');

    //t.PrevOrder();
    //t.PostOrder();
    t.GetKLevel(1);
}