数据结构之树的创建及非递归遍历

来源：互联网发布：组成数据的基本单位编辑：程序博客网时间：2024/06/05 08:27

1，树的递归创建
创建树的类，先创建struct TreeNode的节点
对于 char* ch=”abd###ce##f”的字符串创建树，遇到#为空
2，特殊情况：记得对节点指针的有效性判断

template<class T>struct TreeNode{    TreeNode()    {}    TreeNode(T value)    {        data = value;        LeftTree = NULL;        RightTree = NULL;    }    T data;    TreeNode<T> *LeftTree;    TreeNode<T> *RightTree;};template<class T>class Tree{public:    Tree()        :_pRoot(NULL)    {}    Tree(T* arr, size_t size)        :_pRoot(NULL)    {        size_t index = 0;        CreatTree(_pRoot, arr, size, index);    }    Tree(const Tree<T>& p)    {        if (p._pRoot != NULL)            _pRoot = CopyTree(p._pRoot);    }    Tree<T>& operator=(Tree<T>& p)    {        if (&p != this)        {            if (_pRoot != NULL)            {                Destory(_pRoot);            }            _pRoot = CopyTree(p._pRoot);        }        return  *this;    }    ~Tree()    {        if (_pRoot != NULL)        {            Destory(_pRoot);        }    }    }    void CreatTree(TreeNode<T> *& pRoot, T *arr, size_t size, size_t &index)    {        if (pRoot == NULL && index<size && arr[index] != '#')        {            pRoot = new TreeNode<T>(arr[index]);            CreatTree(pRoot->LeftTree, arr, size, ++index);            CreatTree(pRoot->RightTree, arr, size, ++index);        }    }    TreeNode<T> *& CopyTree(TreeNode<T>* p)    {        TreeNode<T> * newpRoot;        if (p != NULL)        {            newpRoot = new TreeNode<T>(p->data);            newpRoot->LeftTree = CopyTree(p->LeftTree);            newpRoot->RightTree = CopyTree(p->RightTree);            return newpRoot;        }    }    void Destory(TreeNode<T> *& pRoot)    {        if (pRoot != NULL)        {            Destory(pRoot->LeftTree);            Destory(pRoot->RightTree);            delete  pRoot;            pRoot = NULL;        }    }

2树的非递归遍历

void RootFrontTree()    {        std::stack<TreeNode<T>*> s;        TreeNode<T>*  pCur = _pRoot;        s.push(pCur);        while (!s.empty())        {            TreeNode<T>* newTop = s.top();            cout << newTop->data;            s.pop();            if (newTop->RightTree != NULL)                s.push(newTop->RightTree);            if (newTop->LeftTree != NULL)                s.push(newTop->LeftTree);        }    }    void RootMidTree()    {        std::stack<TreeNode<T>*> s;        TreeNode<T>*  pCur = _pRoot;        while (!s.empty() || pCur != NULL)  //当把根的左子树遍历完，根节点也pop出来时，栈可能为空        {            while (pCur)          //找到最左边的：最左边的没左子树            {                s.push(pCur);                pCur = pCur->LeftTree;            }            TreeNode<T>* newTop = s.top();            if (newTop->RightTree == NULL)            {                cout << newTop->data;                s.pop();            }            else            {                cout << newTop->data;                pCur = newTop->RightTree;                s.pop();            }        }    }    void RootBackTree()    {        std::stack<TreeNode<T>*> s;        TreeNode<T>*  pCur = _pRoot;        TreeNode<T>* per = NULL;        while (!s.empty() || pCur != NULL) //刚进时为空        {            while (pCur)          //找到最左边的：最左边的没左子树            {                s.push(pCur);                pCur = pCur->LeftTree;            }            TreeNode<T>* newTop = s.top();            if (newTop->RightTree == NULL || per == newTop->RightTree)//打印1.没右子树 2.有右子树，但已经刚被打印过了            {                cout << newTop->data;                per = newTop;                s.pop();            }            else            {                pCur = newTop->RightTree;            }        }    }

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