[编程之美-14]求二叉树中节点的最大距离

题目:如果我们把二叉树看成一个图，父子节点之间的连线看成是双向的，我们姑且定义”距离”为两节点之间边的个数。写一个程序，求一棵二叉树中相距最远的两个节点之间的距离. 
例如: 
10 
/ \ 
5 12 
/ \ 
4 7 
这棵树的话,最大距离为3.分别路径为4,5,10,12共3条边,7,5,10,12共3条边,所以最大距离为3.

递归的思想,分别考虑左右子树的,从根节点开始.

代码如下:

#include<iostream>using namespace std;struct BiTreeNode{    int m_nValue;    BiTreeNode *m_pleft;    BiTreeNode *m_pright;    int m_nMaxLeft;    int m_nMaxRight;};int nMaxLen = 0;void findMaxLen(BiTreeNode *pRoot);void addBiTreeNode(BiTreeNode *&pCurrent, int value);int main(){    BiTreeNode *pRoot = NULL;    addBiTreeNode(pRoot, 10);    addBiTreeNode(pRoot, 5);    addBiTreeNode(pRoot, 4);    addBiTreeNode(pRoot, 7);    addBiTreeNode(pRoot, 12);    findMaxLen(pRoot);    cout<<nMaxLen<<endl;    return 0;}void findMaxLen(BiTreeNode *pRoot){    if(pRoot == NULL)        return ;    if(pRoot->m_pleft == NULL)        pRoot->m_nMaxLeft = 0;    if(pRoot->m_pright == NULL)        pRoot->m_nMaxRight = 0;    if(pRoot->m_pleft != NULL)        findMaxLen(pRoot->m_pleft);    if(pRoot->m_pright != NULL)        findMaxLen(pRoot->m_pright);    if(pRoot->m_pleft != NULL)    {        int nTempMax = 0;        if(pRoot->m_pleft->m_nMaxLeft > pRoot->m_pleft->m_nMaxRight)            nTempMax = pRoot->m_pleft->m_nMaxLeft;        else            nTempMax = pRoot->m_pleft->m_nMaxRight;        pRoot->m_nMaxLeft = nTempMax + 1;    }    if(pRoot->m_pright != NULL)    {        int nTempMax = 0;        if(pRoot->m_pright->m_nMaxLeft > pRoot->m_pright->m_nMaxRight)            nTempMax = pRoot->m_pright->m_nMaxLeft;        else            nTempMax = pRoot->m_pright->m_nMaxRight;        pRoot->m_nMaxRight = nTempMax + 1;    }    if(pRoot->m_nMaxLeft + pRoot->m_nMaxRight > nMaxLen)        nMaxLen = pRoot->m_nMaxLeft + pRoot->m_nMaxRight;   }void addBiTreeNode(BiTreeNode *&pCurrent, int value){    if(pCurrent == NULL)    {        BiTreeNode *pBiTree = new BiTreeNode();        pBiTree->m_nValue = value;        pBiTree->m_pleft = NULL;        pBiTree->m_pright = NULL;        pCurrent = pBiTree;    }    else    {        if((pCurrent->m_nValue) > value)            addBiTreeNode(pCurrent->m_pleft, value);        else if((pCurrent->m_nValue) < value)            addBiTreeNode(pCurrent->m_pright, value);       }}