树的非递归算法（第一次用手写的代码）

 

#ifndef BINARY_TREE
#define  BINARY_TREE
#include < stack >
#include < iostream >
using   namespace  std;
template < class  T >   class  BinaryTree;
template < class  T >
class  BTNode
{
public:
    BTNode(){lChild=rChild=NULL;}
    BTNode(const T&x)
    {
        element=x;
        lChild=rChild=NULL;
    }
    BTNode(const T& x,BTNode<T>*l,BTNode<T>* r)
    {
        element=x;lChild=l;rChild=r;
    }
    friend class BinaryTree<T>;
private:
    T element;
    BTNode<T>* lChild,*rChild;
    static stack<BTNode<T>*> s;
} ;
template < class  T >
stack < BTNode < T >*>  BTNode < T > ::s;

template < class  T >
class  BinaryTree
{
public:
    BinaryTree(){root=NULL;}
    bool IsEmpty()const{return root==NULL}
    void Clear();
    bool Root(T& x)const;
    void MakeTree(const T& x,BinaryTree<T>& left,BinaryTree<T>& right);
    void BreakTree(T& x,BinaryTree<T>& left,BinaryTree<T>& right);
    void PreOrder();
protected:
    BTNode<T>* root;
private:
    void PreOrder(BTNode<T>*current);
} ;

#endif // BINARY_TREE

template < class  T >
bool  BinaryTree < T > ::Root(T  & x) const
{
    if(root){
        x=root->element;return true;
    }
    else return false;
}

template < class  T >
void  BinaryTree < T > ::MakeTree( const  T &  x,BinaryTree < T >&  left,BinaryTree < T >&  right)
{
    if(root||&left==&right) return;
    root=new BTNode<T>(x,left.root,right.root);
    left.root=right.root=NULL;
}

template < class  T >
void  BinaryTree < T > ::BreakTree(T &  x,BinaryTree < T >&  left,BinaryTree < T >&  right)
{
    if(root||&left==&right||left.root==right.root) return;
    x=root->element;
    left.root=root->lChild;right.root=root->rChild;
    delete root;root=NULL;//
}

template < class  T >
void  BinaryTree < T > ::PreOrder(BTNode < T >*  current)
{
loop:
    while(current){
        Visit(current->element);
        if(current->rChild)
            BTNode<T>::s.push(current->rChild);
        current=current->lChild;
    }
    current=BTNode<T>::s.top();Visit(current->element);BTNode<T>::s.pop();
    if(BTNode<T>::s.empty()) return;
    else goto loop;
}

template < class  T >
void  BinaryTree < T > ::PreOrder()
{
    if(root)
        PreOrder(root);
    if(root->rChild)
        PreOrder(root->rChild);
}