※数据结构※→☆非线性结构(tree)☆============哈夫曼树 链式存储结构(tree Huffman list)(二十三)
哈夫曼树 (Huffman Tree)
给定n个权值作为n个叶子结点,构造一棵二叉树,若带权路径长度达到最小,称这样的二叉树为最优二叉树,也称为哈夫曼树(Huffman tree)。
哈夫曼树(霍夫曼树)又称为最优树.
1、路径和路径长度
在一棵树中,从一个结点往下可以达到的孩子或孙子结点之间的通路,称为路径。通路中分支的数目称为路径长度。若规定根结点的层数为1,则从根结点到第L层结点的路径长度为L-1。
2、结点的权及带权路径长度
若将树中结点赋给一个有着某种含义的数值,则这个数值称为该结点的权。结点的带权路径长度为:从根结点到该结点之间的路径长度与该结点的权的乘积。
3、树的带权路径长度
树的带权路径长度规定为所有叶子结点的带权路径长度之和,记为WPL。
哈夫曼树构造过程
假设有n个权值,则构造出的哈夫曼树有n个叶子结点。 n个权值分别设为 w1、w2、…、wn,则哈夫曼树的构造规则为:

构造过程中,需要使用优先级队列,由于优先级队列存储的仅仅只是指针,因此需要使用伪函数(操作符operator () )自定义排序。
函数对象(伪函数)
实现了一个"()"操作符,这样就允许把这个类像函数一样使用,我们把这样的类称为函数对象,或称做伪函数。可以把实例当作一个函数来使用。
优点:使用仿函数就像使用一个普通的函数一样,但是它的实现可以访问仿函数中所有的成员变量来进行通行;而普通函数若要通信就只能依靠全局变量了。
函数对象顾名思义,就是在某种方式上表现的象一个函数的对象。典型的,它是指一个类的实例,这个类定义了应用操作符operator()。
函数对象是比函数更加通用的概念,因为函数对象可以定义跨越多次调用的可持久的部分(类似静态局部变量),同时又能从对象的外面进行初始化和检查(和静态局部变量不同)
树的四种遍历
1.先序遍历 (仅二叉树)
指先访问根,然后访问孩子的遍历方式
2.中序遍历(仅二叉树)
指先访问左(右)孩子,然后访问根,最后访问右(左)孩子的遍历方式
3.后序遍历(仅二叉树)
指先访问孩子,然后访问根的遍历方式
4.层次遍历
一层一层的访问,所以一般用广度优先遍历。
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树结点 链式存储结构(tree node list)
结点:
包括一个数据元素及若干个指向其它子树的分支;例如,A,B,C,D等。在数据结构的图形表示中,对于数据集合中的每一个数据元素用中间标有元素值的方框表示,一般称之为数据结点,简称结点。
在C语言中,链表中每一个元素称为“结点”,每个结点都应包括两个部分:一为用户需要用的实际数据;二为下一个结点的地址,即指针域和数据域。
数据结构中的每一个数据结点对应于一个储存单元,这种储存单元称为储存结点,也可简称结点
树结点(树节点):
树节点相关术语:
节点的度:一个节点含有的子树的个数称为该节点的度;叶节点或终端节点:度为0的节点称为叶节点;非终端节点或分支节点:度不为0的节点;双亲节点或父节点:若一个结点含有子节点,则这个节点称为其子节点的父节点;孩子节点或子节点:一个节点含有的子树的根节点称为该节点的子节点;兄弟节点:具有相同父节点的节点互称为兄弟节点;节点的层次:从根开始定义起,根为第1层,根的子结点为第2层,以此类推;堂兄弟节点:双亲在同一层的节点互为堂兄弟;节点的祖先:从根到该节点所经分支上的所有节点;子孙:以某节点为根的子树中任一节点都称为该节点的子孙。根据树结点的相关定义,采用“双亲孩子表示法”。其属性如下:
2.孩子表示法
1.多重链表:每个结点有多个指针域,分别指向其子树的根
1)结点同构:结点的指针个数相等,为树的度k,这样n个结点度为k的树必有n(k-1)+1个空链域.
2)结点不同构:结点指针个数不等,为该结点的度d
2.孩子链表:每个结点的孩子结点用单链表存储,再用含n个元素的结构数组指向每个孩子链表
3.双亲孩子表示法
1.双亲表示法,PARENT(T,x)可以在常量时间内完成,但是求结点的孩子时需要遍历整个结构。
2.孩子链表表示法,适于那些涉及孩子的操作,却不适于PARENT(T,x)操作。
3.将双亲表示法和孩子链表表示法合在一起,可以发挥以上两种存储结构的优势,称为带双亲的孩子链表表示法
4.双亲孩子兄弟表示法 (二叉树专用)
又称为二叉树表示法,以二叉链表作为树的存储结构。
链式存储结构
在计算机中用一组任意的存储单元存储线性表的数据元素(这组存储单元可以是连续的,也可以是不连续的).
它不要求逻辑上相邻的元素在物理位置上也相邻.因此它没有顺序存储结构所具有的弱点,但也同时失去了顺序表可随机存取的优点.
链式存储结构特点:
1、比顺序存储结构的存储密度小 (每个节点都由数据域和指针域组成,所以相同空间内假设全存满的话顺序比链式存储更多)。
2、逻辑上相邻的节点物理上不必相邻。
3、插入、删除灵活 (不必移动节点,只要改变节点中的指针)。
4、查找结点时链式存储要比顺序存储慢。
5、每个结点是由数据域和指针域组成。~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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C++完整个代码示例(代码在VS2005下测试可运行)
AL_TreeNodeBinList.h
#ifdef TEST_AL_TREEHUFFMANLISTAL_TreeHuffmanList<DWORD> cTreeHuffman;BOOL bEmpty = cTreeHuffman.IsEmpty();std::cout<<bEmpty<<std::endl;const AL_TreeNodeBinList<DWORD>* pConstRootNode = cTreeHuffman.GetRootNode();AL_TreeNodeBinList<DWORD>* pRootNode = const_cast<AL_TreeNodeBinList<DWORD>*>(pConstRootNode);std::cout<<pRootNode<<std::endl;DWORD dwDegree = cTreeHuffman.GetDegree();std::cout<<dwDegree<<std::endl;DWORD dwHeight = cTreeHuffman.GetHeight();std::cout<<dwHeight<<std::endl;DWORD dwNodesNum = cTreeHuffman.GetNodesNum();std::cout<<dwNodesNum<<std::endl;DWORD dwWeight = 0x01;cTreeHuffman.InsertRoot(0, dwWeight);pConstRootNode = cTreeHuffman.GetRootNode();pRootNode = const_cast<AL_TreeNodeBinList<DWORD>*>(pConstRootNode);std::cout<<pRootNode<<std::endl;dwWeight += 2;cTreeHuffman.InsertLeftAtNode(pRootNode, 10, dwWeight);const AL_TreeNodeBinList<DWORD>* pConstTreeNode = cTreeHuffman.GetChildNodeLeftAtNode(pRootNode);AL_TreeNodeBinList<DWORD>* pTreeNode = const_cast<AL_TreeNodeBinList<DWORD>*>(pConstTreeNode);std::cout<<pTreeNode<<std::endl;dwWeight += 2;cTreeHuffman.InsertLeftAtNode(pTreeNode, 20, dwWeight);dwWeight += 2;cTreeHuffman.InsertRightAtNode(pTreeNode, 21, dwWeight);const AL_TreeNodeBinList<DWORD>* pConstTreeNode20 = cTreeHuffman.GetChildNodeLeftAtNode(pTreeNode);AL_TreeNodeBinList<DWORD>* pTreeNode20 = const_cast<AL_TreeNodeBinList<DWORD>*>(pConstTreeNode20);std::cout<<pTreeNode<<std::endl;dwWeight += 2;cTreeHuffman.InsertLeftAtNode(pTreeNode20, 30, dwWeight);dwWeight += 2;cTreeHuffman.InsertRightAtNode(pTreeNode20, 31, dwWeight);const AL_TreeNodeBinList<DWORD>* pConstTreeNode31 = cTreeHuffman.GetChildNodeRightAtNode(pConstTreeNode20);AL_TreeNodeBinList<DWORD>* pTreeNode31 = const_cast<AL_TreeNodeBinList<DWORD>*>(pConstTreeNode31);dwWeight += 2;cTreeHuffman.InsertLeftAtNode(pTreeNode31, 40, dwWeight);dwWeight += 2;cTreeHuffman.InsertRightAtNode(pTreeNode31, 41, dwWeight);const AL_TreeNodeBinList<DWORD>* pConstTreeNode30 = cTreeHuffman.GetChildNodeLeftAtNode(pConstTreeNode20);AL_TreeNodeBinList<DWORD>* pTreeNode30 = const_cast<AL_TreeNodeBinList<DWORD>*>(pConstTreeNode30);dwWeight += 2;cTreeHuffman.InsertRightAtNode(pTreeNode30, 999, dwWeight);const AL_TreeNodeBinList<DWORD>* pConstTreeNode999 = cTreeHuffman.GetChildNodeRightAtNode(pConstTreeNode30);AL_TreeNodeBinList<DWORD>* pTreeNode999 = const_cast<AL_TreeNodeBinList<DWORD>*>(pConstTreeNode999);dwWeight += 2;cTreeHuffman.InsertLeftAtNode(pTreeNode999, 888, dwWeight);const AL_TreeNodeBinList<DWORD>* pConstTreeNode41 = cTreeHuffman.GetChildNodeRightAtNode(pConstTreeNode31);AL_TreeNodeBinList<DWORD>* pTreeNode41 = const_cast<AL_TreeNodeBinList<DWORD>*>(pConstTreeNode41);dwWeight += 2;cTreeHuffman.InsertRightAtNode(pTreeNode41, 52, dwWeight);const AL_TreeNodeBinList<DWORD>* pConstTreeNode33 = cTreeHuffman.GetChildNodeRightAtNode(pTreeNode20);AL_TreeNodeBinList<DWORD>* pTreeNode33 = const_cast<AL_TreeNodeBinList<DWORD>*>(pConstTreeNode33);if (NULL != pTreeNode) {std::cout<<pTreeNode->GetLevel()<<" "<<pTreeNode->GetData()<<" "<<pTreeNode->GetDegree()<<std::endl;std::cout<<pTreeNode->IsLeaf()<<" "<<pTreeNode->IsBranch()<<" "<<pTreeNode->IsParent(pTreeNode)<<" "<<pTreeNode->IsParent(pTreeNode33)<<std::endl;}if (NULL != pTreeNode20) {std::cout<<pTreeNode20->GetLevel()<<" "<<pTreeNode20->GetData()<<" "<<pTreeNode20->GetDegree()<<std::endl;std::cout<<pTreeNode20->IsLeaf()<<" "<<pTreeNode20->IsBranch()<<" "<<pTreeNode20->IsParent(pTreeNode)<<" "<<pTreeNode20->IsParent(pTreeNode33)<<std::endl;}if (NULL != pTreeNode33) {std::cout<<pTreeNode33->GetLevel()<<" "<<pTreeNode33->GetData()<<" "<<pTreeNode33->GetDegree()<<std::endl;std::cout<<pTreeNode33->IsLeaf()<<" "<<pTreeNode33->IsBranch()<<" "<<pTreeNode33->IsParent(pTreeNode)<<" "<<pTreeNode33->IsParent(pTreeNode33)<<std::endl;}const AL_TreeNodeBinList<DWORD>*pChild = NULL;pChild = cTreeHuffman.GetChildNodeRightAtNode(pTreeNode);if (NULL != pChild) {std::cout<<pChild->GetLevel()<<" "<<pChild->GetData()<<" "<<pChild->GetDegree()<<std::endl;std::cout<<pChild->IsLeaf()<<" "<<pChild->IsBranch()<<" "<<pChild->IsParent(pTreeNode)<<" "<<pChild->IsParent(pTreeNode33)<<std::endl;}pChild = cTreeHuffman.GetChildNodeLeftAtNode(pTreeNode);if (NULL != pChild) {std::cout<<pChild->GetLevel()<<" "<<pChild->GetData()<<" "<<pChild->GetDegree()<<std::endl;std::cout<<pChild->IsLeaf()<<" "<<pChild->IsBranch()<<" "<<pChild->IsParent(pTreeNode)<<" "<<pChild->IsParent(pTreeNode33)<<std::endl;}pChild = cTreeHuffman.GetChildNodeLeftAtNode(pTreeNode);if (NULL != pChild) {std::cout<<pChild->GetLevel()<<" "<<pChild->GetData()<<" "<<pChild->GetDegree()<<std::endl;std::cout<<pChild->IsLeaf()<<" "<<pChild->IsBranch()<<" "<<pChild->IsParent(pTreeNode)<<" "<<pChild->IsParent(pTreeNode33)<<std::endl;}pChild = cTreeHuffman.GetChildNodeRightAtNode(pTreeNode);if (NULL != pChild) {std::cout<<pChild->GetLevel()<<" "<<pChild->GetData()<<" "<<pChild->GetDegree()<<std::endl;std::cout<<pChild->IsLeaf()<<" "<<pChild->IsBranch()<<" "<<pChild->IsParent(pTreeNode)<<" "<<pChild->IsParent(pTreeNode33)<<std::endl;}pChild = cTreeHuffman.GetChildNodeRightAtNode(pTreeNode);if (NULL != pChild) {std::cout<<pChild->GetLevel()<<" "<<pChild->GetData()<<" "<<pChild->GetDegree()<<std::endl;std::cout<<pChild->IsLeaf()<<" "<<pChild->IsBranch()<<" "<<pChild->IsParent(pTreeNode)<<" "<<pChild->IsParent(pTreeNode33)<<std::endl;}bEmpty = cTreeHuffman.IsEmpty();std::cout<<bEmpty<<std::endl;dwDegree = cTreeHuffman.GetDegree();std::cout<<dwDegree<<std::endl;dwHeight = cTreeHuffman.GetHeight();std::cout<<dwHeight<<std::endl;dwNodesNum = cTreeHuffman.GetNodesNum();std::cout<<dwNodesNum<<std::endl;AL_ListSingle<DWORD> cList;DWORD dwData;BOOL bSibling = cTreeHuffman.GetSiblingAtNode(pTreeNode, cList);if (TRUE == bSibling) {for (DWORD dwCnt=0; dwCnt<cList.Length(); dwCnt++) {if (TRUE == cList.Get(dwCnt, dwData)) {std::cout<<dwData<<", ";}}std::cout<<std::endl;}cList.Clear();bSibling = cTreeHuffman.GetSiblingAtNode(pTreeNode20, cList);if (TRUE == bSibling) {for (DWORD dwCnt=0; dwCnt<cList.Length(); dwCnt++) {if (TRUE == cList.Get(dwCnt, dwData)) {std::cout<<dwData<<", ";}}std::cout<<std::endl;}cList.Clear();BOOL bAncestor = cTreeHuffman.GetAncestorAtNode(pRootNode, cList);if (TRUE == bAncestor) {for (DWORD dwCnt=0; dwCnt<cList.Length(); dwCnt++) {if (TRUE == cList.Get(dwCnt, dwData)) {std::cout<<dwData<<", ";}}std::cout<<std::endl;}bAncestor = cTreeHuffman.GetAncestorAtNode(pTreeNode33, cList);if (TRUE == bAncestor) {for (DWORD dwCnt=0; dwCnt<cList.Length(); dwCnt++) {if (TRUE == cList.Get(dwCnt, dwData)) {std::cout<<dwData<<", ";}}std::cout<<std::endl;}cList.Clear();BOOL bDescendant = cTreeHuffman.GetDescendantAtNode(pRootNode, cList);if (TRUE == bDescendant) {for (DWORD dwCnt=0; dwCnt<cList.Length(); dwCnt++) {if (TRUE == cList.Get(dwCnt, dwData)) {std::cout<<dwData<<", ";}}std::cout<<std::endl;}cList.Clear();bDescendant = cTreeHuffman.GetDescendantAtNode(pTreeNode33, cList);if (TRUE == bDescendant) {for (DWORD dwCnt=0; dwCnt<cList.Length(); dwCnt++) {if (TRUE == cList.Get(dwCnt, dwData)) {std::cout<<dwData<<", ";}}std::cout<<std::endl;}cList.Clear();BOOL bOrder = cTreeHuffman.PreOrderTraversal(cList);if (TRUE == bOrder) {for (DWORD dwCnt=0; dwCnt<cList.Length(); dwCnt++) {if (TRUE == cList.Get(dwCnt, dwData)) {std::cout<<dwData<<", ";}}std::cout<<std::endl;}cList.Clear();bOrder = cTreeHuffman.InOrderTraversal(cList);if (TRUE == bOrder) {for (DWORD dwCnt=0; dwCnt<cList.Length(); dwCnt++) {if (TRUE == cList.Get(dwCnt, dwData)) {std::cout<<dwData<<", ";}}std::cout<<std::endl;}cList.Clear();bOrder = cTreeHuffman.PostOrderTraversal(cList);if (TRUE == bOrder) {for (DWORD dwCnt=0; dwCnt<cList.Length(); dwCnt++) {if (TRUE == cList.Get(dwCnt, dwData)) {std::cout<<dwData<<", ";}}std::cout<<std::endl;}cList.Clear();bOrder = cTreeHuffman.LevelOrderTraversal(cList);if (TRUE == bOrder) {for (DWORD dwCnt=0; dwCnt<cList.Length(); dwCnt++) {if (TRUE == cList.Get(dwCnt, dwData)) {std::cout<<dwData<<", ";}}std::cout<<std::endl;}cList.Clear();BOOL bConvertToHuffman = cTreeHuffman.ConvertToHuffman();std::cout<<bConvertToHuffman<<std::endl;AL_ListSingle<DWORD> cListWeight;bOrder = cTreeHuffman.LevelOrderTraversal(cList, cListWeight);if (TRUE == bOrder) {for (DWORD dwCnt=0; dwCnt<cList.Length(); dwCnt++) {if (TRUE == cList.Get(dwCnt, dwData) && TRUE == cListWeight.Get(dwCnt, dwWeight)) {std::cout<<"["<<dwData<<", "<<dwWeight<<"]"<<", ";}}std::cout<<std::endl;}cList.Clear();cListWeight.Clear();dwDegree = cTreeHuffman.GetDegree();std::cout<<dwDegree<<std::endl;dwHeight = cTreeHuffman.GetHeight();std::cout<<dwHeight<<std::endl;dwNodesNum = cTreeHuffman.GetNodesNum();std::cout<<dwNodesNum<<std::endl;cTreeHuffman.RemoveNode(pTreeNode20);bConvertToHuffman = cTreeHuffman.ConvertToHuffman();std::cout<<bConvertToHuffman<<std::endl;bOrder = cTreeHuffman.LevelOrderTraversal(cList, cListWeight);if (TRUE == bOrder) {for (DWORD dwCnt=0; dwCnt<cList.Length(); dwCnt++) {if (TRUE == cList.Get(dwCnt, dwData) && TRUE == cListWeight.Get(dwCnt, dwWeight)) {std::cout<<"["<<dwData<<", "<<dwWeight<<"]"<<", ";}}std::cout<<std::endl;}bEmpty = cTreeHuffman.IsEmpty();std::cout<<bEmpty<<std::endl;dwDegree = cTreeHuffman.GetDegree();std::cout<<dwDegree<<std::endl;dwHeight = cTreeHuffman.GetHeight();std::cout<<dwHeight<<std::endl;dwNodesNum = cTreeHuffman.GetNodesNum();std::cout<<dwNodesNum<<std::endl;#endif






