遞歸實現二叉樹

對于二叉樹的實現主要運用遞歸進行實現，代碼如下：

#include <assert.h>

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

{

protected:

BinaryTreeNode<T> *_root;

BinaryTreeNode<T> *_creattree(const T a[], size_t size, size_t &index, T invalid)

{

BinaryTreeNode<T> * root = NULL;

if (index < size && a[index] != invalid)

{

root = new BinaryTreeNode<T>(a[index]);

root->_left = _creattree(a, size, ++index, invalid);

root->_right = _creattree(a, size, ++index, invalid);

}

return root;

}

void _prevorder(const BinaryTreeNode<T> *root)

{

if (root == NULL)

return;

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

_prevorder(root->_left);

_prevorder(root->_right);*/

}

void _inorder(const BinaryTreeNode<T> *root)

{

if (root == NULL)

return;

_inorder(root->_left);

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

_inorder(root->_right);

}

void _postorder(const BinaryTreeNode<T> *root)

{

if (root == NULL)

return;

_postorder(root->_left);

_postorder(root->_right);

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

}

size_t  _leafsize(const BinaryTreeNode<T> *root)

{

if (root == NULL)

return 0;

if (root->_left == NULL && root->_right == NULL)

return 1;

return _leafsize(root->_left) + _leafsize(root->_right);

}

size_t _size(const BinaryTreeNode<T> *root)

{

if (root == NULL)

return 0;

return _size(root->_left) + _size(root->_right) + 1;

}

size_t _Depth(const BinaryTreeNode<T> *root)

{

if (root == NULL)

return 0;

int left = _Depth(root->_left);

int right = _Depth(root->_right);

return left > right ? left + 1 : right + 1;

}

public:

BinaryTree(T const*a = "", size_t size = 0)

{

size_t index = 0;

_root = _creattree(a, size, index, '#');

}

void prevorder()

{

_prevorder(_root);

}

void inorder()

{

_inorder(_root);

}

void postorder()

{

_postorder(_root);

}

size_t size()

{

int count = _size(_root);

return count;

}

size_t leafsize()

{

int count = _leafsize(_root);

return count;

}

size_t Depth()

{

int depth = _Depth(_root);

return depth;

}

};

void test()

{

BinaryTree<char> b("12#3##45#6#7##8", 15);

/*b.levelorder();*/

/*BinaryTree<char> b1;

b1 = b;*/

/*cout<<b.Depth();*/

/*cout << b.size();*/

b.postorder();

/*cout << b.leafsize();*/

}

int main()

{

test();

getchar();

return 0;

}