线索化二叉树BinaryTreeThreading

/******************************************************************************************Copyright (c) Inc.(2016), All rights reserved.Purpose: 二叉树的前/中/后序线索化Author: MaJingReviser: yyyCreated Time: 2016-9******************************************************************************************/#pragma onceenum PointerTag {THREAD, LINK};template<class T>struct BinaryTreeNodeThd{T _data;// 数据BinaryTreeNodeThd<T>* _left;// 左孩子BinaryTreeNodeThd<T>* _right;// 右孩子BinaryTreeNodeThd<T>* _parent;// 父节点（为后序遍历的线索化而生）PointerTag_leftTag;// 左孩子线索标志PointerTag_rightTag;// 右孩子线索标志BinaryTreeNodeThd(const T& x):_data(x),_left(NULL),_right(NULL),_parent(NULL),_leftTag(LINK),_rightTag(LINK){}};template<class T>class BinaryTreeThd{public:BinaryTreeThd():_root(NULL){}BinaryTreeThd(T array[], size_t size){int index = 0;_CreateTree(_root, array, size, index);}void InThreading(){BinaryTreeNodeThd<T>* prev = NULL;_InThreading(_root, prev);}void PrevThreading(){BinaryTreeNodeThd<T>* prev = NULL;_PrevThreading(_root, prev);}void PostThreading(){BinaryTreeNodeThd<T>* prev = NULL;_PostThreading(_root, prev);}void InOrder(){cout<<"InOrder:";_InOrder(_root);cout<<endl;}void PrevOrder(){cout<<"PrevOrder:";_PrevOrder(_root);cout<<endl;}void PostOrder(){cout<<"PostOrder:";_PostOrder(_root);cout<<endl;}protected:// 构建二叉树void _CreateTree(BinaryTreeNodeThd<T>*& root, T array1[], size_t size, int& index){if (index < size && array1[index] != '#'){root = new BinaryTreeNodeThd<T>(array1[index]);_CreateTree(root->_left, array1, size, ++index);_CreateTree(root->_right, array1, size, ++index);if (root->_left){root->_left->_parent = root;}if (root->_right){root->_right->_parent = root;}}}void _InThreading(BinaryTreeNodeThd<T>* cur, BinaryTreeNodeThd<T>*& prev){if (cur){// 1.线索化左子树_InThreading(cur->_left, prev);// 2.线索化当前节点的前驱if(cur->_left == NULL){cur->_leftTag = THREAD;cur->_left = prev;}// 3.线索化前驱节点的后继节点if (prev && prev->_right == NULL){prev->_rightTag = THREAD;prev->_right = cur;}prev = cur;// 4.线索化右子树_InThreading(cur->_right, prev);}}void _PrevThreading(BinaryTreeNodeThd<T>* cur, BinaryTreeNodeThd<T>*& prev){if(cur){// 1.线索化当前节点的前驱if (cur->_left == NULL){cur->_leftTag = THREAD;cur->_left = prev;}// 2.线索化前一个节点的后继为当前节点if (prev && prev->_right == NULL){prev->_rightTag = THREAD;prev->_right = cur;}prev = cur;// 只有LINK的节点才需要递归，否则前序遍历的节点已线索化。if (cur->_leftTag == LINK)_PrevThreading(cur->_left, prev);if (cur->_rightTag == LINK)_PrevThreading(cur->_right, prev);}}void _PostThreading(BinaryTreeNodeThd<T>* cur, BinaryTreeNodeThd<T>*& prev){if(cur){// 只有LINK的节点才需要递归，否则前序遍历的节点已线索化。if (cur->_leftTag == LINK)_PostThreading(cur->_left, prev);if (cur->_rightTag == LINK)_PostThreading(cur->_right, prev);// 1.线索化当前节点的前驱if (cur->_left == NULL){cur->_leftTag = THREAD;cur->_left = prev;}// 2.线索化前一个节点的后继为当前节点if (prev && prev->_right == NULL){prev->_rightTag = THREAD;prev->_right = cur;}prev = cur;}}void _InOrder(BinaryTreeNodeThd<T>* cur){while(cur){// 走左子树，找到第一个要访问的前驱节点while (cur && cur->_leftTag == LINK){cur = cur->_left;}// 访问当前节点cout<<cur->_data<<" ";// 访问连接在一起的后继节点while (cur->_rightTag == THREAD && cur->_right){cur = cur->_right;cout<<cur->_data<<" ";}cur = cur->_right;}}void _PrevOrder(BinaryTreeNodeThd<T>* cur){while(cur){// 前序遍历路径上的所经节点while (cur){// 访问当前节点cout<<cur->_data<<" ";if (cur->_leftTag == THREAD)break;cur = cur->_left;}// 访问连接在一起的后继节点--这样处理有bug/*while (cur->_rightTag == THREAD && cur->_right){cur = cur->_right;cout<<cur->_data<<" ";}cur = cur->_right;*///// 不论是Thread后继节点，还是右子树都直接跳转过去访问// 所有节点都当成二叉树的左路节点来访问//cur = cur->_right;}}void _PostOrder(BinaryTreeNodeThd<T>* root){BinaryTreeNodeThd<T>* cur = root;BinaryTreeNodeThd<T>* prev = NULL;while (cur){// 走左子树，先找到最左节点while (cur && cur->_leftTag == LINK){cur = cur->_left;}// 访问后继节点while(cur->_rightTag == THREAD){cout<<cur->_data<<" ";prev = cur;cur = cur->_right;}if (cur == root){cout<<cur->_data<<" ";break;}// 如果当前节点的右节点已访问，则访问当前节点并跳到父节点while(cur->_right == prev){cout<<cur->_data<<" ";prev = cur;if (cur == root)return;cur = cur->_parent;}// 跳转到当前节点的右树，当做子树访问if (cur->_rightTag == LINK)cur = cur->_right;}}private:BinaryTreeNodeThd<T>* _root;};// 测试线索化二叉树void TestBinaryTreeThd(){int array1[20] = {1, 2, 3, '#', '#', 4, '#', '#', 5, 6};BinaryTreeThd<int> t1(array1, 10);t1.InThreading();t1.InOrder();BinaryTreeThd<int> t2(array1, 10);t2.PrevThreading();t2.PrevOrder();BinaryTreeThd<int> t3(array1, 10);t3.PostThreading();t3.PostOrder();cout<<"==================================="<<endl;int array2[15] = {1,2,'#',3,'#','#',4,5,'#',6,'#',7,'#','#',8};BinaryTreeThd<int> t4(array2, 15);t4.InThreading();t4.InOrder();BinaryTreeThd<int> t5(array2, 15);t5.PostThreading();t5.PostOrder();BinaryTreeThd<int> t6(array2, 15);t6.PrevThreading();t6.PrevOrder();}