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题目：输入一棵二叉搜索树，将该二叉搜索树转换成一个排序的双向链表。要求不能创建任何新的结点，只能调整树中结点指针的指向。比如输入下图中左边儿茶搜索树，则输出转换后的排序双向链表。
10
/ 6 14
/ \ / 4 8 12 16
4=6=8=10=12=14=16
将二叉搜索树转化为有序双向链表，类似于中序遍历，中序遍历的结果就是一个排序的数字。因此在程序中以中序遍历树，当遍历左子树到在叶子结点的时候，开始修改指针。
#include<iostream> #include<stdlib.h> using namespace std; struct BinaryTreeNode { int m_nValue; BinaryTreeNode* m_pLeft; BinaryTreeNode* m_pRight; }; //创建二叉树结点 BinaryTreeNode* CreateBinaryTreeNode(int value) { BinaryTreeNode* pNode=new BinaryTreeNode(); pNode->m_nValue=value; pNode->m_pLeft=NULL; pNode->m_pRight=NULL; return pNode; } void ConnectTreeNodes(BinaryTreeNode* pParent,BinaryTreeNode* pLeft,BinaryTreeNode* pRight) { if(pParent!=NULL) { pParent->m_pLeft=pLeft; pParent->m_pRight=pRight; } } void InOrderPrintTree(BinaryTreeNode* pRoot)//中序遍历 { if(pRoot!=NULL) { if(pRoot->m_pLeft!=NULL)// InOrderPrintTree(pRoot->m_pLeft); cout<<"value of this node is "<<pRoot->m_nValue<<endl; if(pRoot->m_pRight!=NULL) InOrderPrintTree(pRoot->m_pRight); } else { cout<<"this node is null."<<endl; } } void Convert(BinaryTreeNode* pNode,BinaryTreeNode** pLastNodeInList) { if(pNode==NULL) return; BinaryTreeNode* pCurrent=pNode; //左子树转换，遍历到左子树的叶子结点 if(pCurrent->m_pLeft!=NULL)//遍历左子树 Convert(pCurrent->m_pLeft,pLastNodeInList); pCurrent->m_pLeft=*pLastNodeInList; if((*pLastNodeInList)!=NULL) (*pLastNodeInList)->m_pRight=pCurrent; *pLastNodeInList=pCurrent; //右子树转换 if(pCurrent->m_pRight!=NULL)//遍历右子树 Convert(pCurrent->m_pRight,pLastNodeInList); } BinaryTreeNode* Convert(BinaryTreeNode* pRoot) { BinaryTreeNode* pLastNodeInList=NULL;//指向双向链表的尾结点 Convert(pRoot,&pLastNodeInList);//转换排序二叉树为双向链表 //求双向链表的头结点 BinaryTreeNode* pHeadOfList=pLastNodeInList; while(pHeadOfList!=NULL&&pHeadOfList->m_pLeft!=NULL) pHeadOfList=pHeadOfList->m_pLeft; return pHeadOfList; } //输出双向链表 void PrintList(BinaryTreeNode* pRoot) { BinaryTreeNode* pNode = pRoot; while(pNode != NULL) { printf("%d\t", pNode->m_nValue); pNode = pNode->m_pRight; } printf("\nPrintList ends.\n"); } void main() { // 10 // / // 6 14 // /\ /// 4 8 12 16 //创建树结点 BinaryTreeNode* pNode10 = CreateBinaryTreeNode(10); BinaryTreeNode* pNode6 = CreateBinaryTreeNode(6); BinaryTreeNode* pNode14 = CreateBinaryTreeNode(14); BinaryTreeNode* pNode4 = CreateBinaryTreeNode(4); BinaryTreeNode* pNode8 = CreateBinaryTreeNode(8); BinaryTreeNode* pNode12 = CreateBinaryTreeNode(12); BinaryTreeNode* pNode16 = CreateBinaryTreeNode(16); //连接树结点 ConnectTreeNodes(pNode10, pNode6, pNode14); ConnectTreeNodes(pNode6, pNode4, pNode8); ConnectTreeNodes(pNode14, pNode12, pNode16); //PrintTree(pNode10); InOrderPrintTree(pNode10);//中序遍历 BinaryTreeNode* pHeadOfList=Convert(pNode10);//获取双向链表头结点 PrintList(pHeadOfList);//输出链表 system("pause"); }
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原文地址：http://www.cnblogs.com/bendantuohai/p/4532530.html
