【100题】二叉排序树转成双向链表

#include <stdio.h>#include <iostream>using namespace std;struct BSTreeNode{    int m_nValue; // value of node    BSTreeNode *m_pLeft; // left child of node    BSTreeNode *m_pRight; // right child of node};typedef BSTreeNode DoubleList;DoubleList * pHead;// 创建二元查找树void createBinarySearchTree(BSTreeNode * & pCurrent, int value){    if (NULL == pCurrent)    {        BSTreeNode * pBSTree = new BSTreeNode();        pBSTree->m_pLeft = NULL;        pBSTree->m_pRight = NULL;        pBSTree->m_nValue = value;        pCurrent = pBSTree;    }    else     {        if ((pCurrent->m_nValue) > value)        {//如果比当前节点值小，则放到左子树            createBinarySearchTree(pCurrent->m_pLeft, value);        }        else if ((pCurrent->m_nValue) < value)        {//如果比当前节点值大，则放到右子树            createBinarySearchTree(pCurrent->m_pRight, value);        }        else        {//否则提示重复插入了。            cout<<"重复加入节点"<<endl;        }    }}BSTreeNode *ConvertNode(BSTreeNode *pNode,bool asRight){if(!pNode){return NULL;}BSTreeNode *pLeft = NULL;BSTreeNode *pRight = NULL;//如果左孩子不空，则递归转换左子树-->双向链表，并返回左子链表的最右端节点(最大值节点)if(pNode->m_pLeft){pLeft = ConvertNode(pNode->m_pLeft,false);}//将当前节点与左子链表的最右端连接起来。if(pLeft){pLeft->m_pRight = pNode;pNode->m_pLeft = pLeft;}//如果右孩子不空，则递归转换右子树-->双向链表，并返回右子链表的最左端的节点(最小值节点)if(pNode->m_pRight){pRight = ConvertNode(pNode->m_pRight,true);}//把当前节点与右子链表上最左端节点连接起来。if(pRight){pNode->m_pRight = pRight;pRight->m_pLeft = pNode;}//BSTreeNode *pTemp = pNode;//如果该分支是右子树，则将指针移动到最左侧if(asRight){while(pTemp->m_pLeft){pTemp = pTemp->m_pLeft;}}else//否则肯定是左子树，则移动指针到最右侧{while(pTemp->m_pRight){pTemp = pTemp->m_pRight;}}return pTemp;}BSTreeNode *Convert(BSTreeNode *pHeadOfTree){return ConvertNode(pHeadOfTree,true);}int main(){    BSTreeNode * pRoot = NULL;    pHead = NULL;    createBinarySearchTree(pRoot, 10);    createBinarySearchTree(pRoot, 4);    createBinarySearchTree(pRoot, 6);    createBinarySearchTree(pRoot, 8);    createBinarySearchTree(pRoot, 12);    createBinarySearchTree(pRoot, 14);    createBinarySearchTree(pRoot, 15);    createBinarySearchTree(pRoot, 16);pHead = Convert(pRoot);//从最左侧开始打印双向链表cout << "从左向右打印：";DoubleList *p = pHead;while(p != NULL){cout << p->m_nValue<<" ";p= p->m_pRight;}//从最右侧开始打印双向链表cout << endl <<"从右向左打印：";while(pHead->m_pRight != NULL){pHead= pHead->m_pRight;}while(pHead != NULL){cout << pHead->m_nValue<<" ";pHead = pHead->m_pLeft;}cout << endl;    return 0;}

 

运行结果：

从左向右打印：4 6 8 10 12 14 15 16
从右向左打印：16 15 14 12 10 8 6 4
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