面试常见算法习题1

/*
2010年 10月18日下午 July
--------------------------------
1.把二元查找树转变成排序的双向链表
 题目：
输入一棵二元查找树，将该二元查找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，只调整指针的指向。
   
   10
   / \
  6  14
 / \ / \
4  8 12 16
   
 转换成双向链表
 4=6=8=10=12=14=16。
   
 首先我们定义的二元查找树 节点的数据结构如下：
 struct BSTreeNode
{
  int m_nValue; // value of node
  BSTreeNode *m_pLeft; // left child of node
  BSTreeNode *m_pRight; // right child of node
};
*/


//引用 245 楼 tree_star 的回复
#include <stdio.h>
#include <iostream.h>


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;
DoubleList * pListIndex;


void convertToDoubleList(BSTreeNode * pCurrent);




// 创建二元查找树
void addBSTreeNode(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)
        {
            addBSTreeNode(pCurrent->m_pLeft, value);
        }
        else if ((pCurrent->m_nValue) < value)
        {
            addBSTreeNode(pCurrent->m_pRight, value);
        }
        else
        {
            //cout<<"重复加入节点"<<endl;
        }
    }
}




// 遍历二元查找树  中序
void ergodicBSTree(BSTreeNode * pCurrent)
{
    if (NULL == pCurrent)
    {        
        return;
    }
    if (NULL != pCurrent->m_pLeft)
    {
        ergodicBSTree(pCurrent->m_pLeft);    
    }


    // 节点接到链表尾部
    convertToDoubleList(pCurrent);


    // 右子树为空
    if (NULL != pCurrent->m_pRight)
    {
        ergodicBSTree(pCurrent->m_pRight);
    }
}






// 二叉树转换成list
void  convertToDoubleList(BSTreeNode * pCurrent)
{


    pCurrent->m_pLeft = pListIndex;
    if (NULL != pListIndex)
    {
        pListIndex->m_pRight = pCurrent;
    }
    else
    {
        pHead = pCurrent;
    }    
    pListIndex = pCurrent;
    cout<<pCurrent->m_nValue<<endl;
}


int main()
{
    BSTreeNode * pRoot = NULL;
    pListIndex = NULL;
    pHead = NULL;
    addBSTreeNode(pRoot, 10);
    addBSTreeNode(pRoot, 4);
    addBSTreeNode(pRoot, 6);
    addBSTreeNode(pRoot, 8);
    addBSTreeNode(pRoot, 12);
    addBSTreeNode(pRoot, 14);
    addBSTreeNode(pRoot, 15);
    addBSTreeNode(pRoot, 16);
    ergodicBSTree(pRoot);
    return 0;
}


///////////////////////////////////////////////
4
6
8
10
12
14
15
16
Press any key to continue
//////////////////////////////////////////////