[編程之美-08]求二元樹的度

題目：輸入一棵二元樹的根結點，求該樹的深度。
從根結點到葉結點依次經過的結點（含根、葉結點）形成樹的一條路徑，最長路徑的長度爲樹的深度。
例如：輸入二元樹：
8
/ /
6 10
// //
5 7 9 11
輸出該樹的深度3。
二元樹的結點定義如下：

struct SBinaryTreeNode // a node of the binary tree
{
      int               m_nValue; // value of node
      SBinaryTreeNode  *m_pLeft;  // left child of node
      SBinaryTreeNode  *m_pRight; // right child of node
};

思想：同[編程之美-07]主要考察還是層序遍歷思想。

代碼如下：

#include<iostream>
#include<deque>
using namespace std;

struct BSTreeNode
{
    int m_nValue;
    BSTreeNode *m_pleft;
    BSTreeNode *m_pright;
};

int depthOfBSTree = 0;

void addBSTreeNode(BSTreeNode *&pCurrent, int value);

void levelOrderBSTree(BSTreeNode *pRoot);



int main()
{
    BSTreeNode *pRoot = NULL;

    addBSTreeNode(pRoot, 8);
    addBSTreeNode(pRoot, 6);
    addBSTreeNode(pRoot, 5);
    addBSTreeNode(pRoot, 7);
    addBSTreeNode(pRoot, 10);
    addBSTreeNode(pRoot, 9);
    addBSTreeNode(pRoot, 11);

    levelOrderBSTree(pRoot);
    cout<<depthOfBSTree<<endl;
    return 0;
}


void levelOrderBSTree(BSTreeNode *pRoot)
{
    if(pRoot == NULL)
        return ;

    deque<BSTreeNode*> que;
    que.push_back(pRoot);

    BSTreeNode *last, *nlast;
    last = pRoot;
    nlast = pRoot;

    while(que.size() != 0)
    {
        BSTreeNode *pCurrent = que.front();
        que.pop_front();

        if(pCurrent->m_pleft != NULL)
        {
            nlast = pCurrent->m_pleft;
            que.push_back(pCurrent->m_pleft);
        }

        if(pCurrent->m_pright != NULL)
        {
            nlast = pCurrent->m_pright;
            que.push_back(pCurrent->m_pright);
        }

        if(pCurrent == last)
        {
            depthOfBSTree ++;
            last = nlast;
        }
    }
}


void addBSTreeNode(BSTreeNode *&pCurrent, int value)
{
    if(pCurrent == NULL)
    {
        BSTreeNode *pBSTree = new BSTreeNode();
        pBSTree->m_nValue = value;
        pBSTree->m_pleft = NULL;
        pBSTree->m_pright = NULL;
        pCurrent = pBSTree;
    }
    else
    {
        if((pCurrent->m_nValue) > value)
            addBSTreeNode(pCurrent->m_pleft, value);
        else if((pCurrent->m_nValue) < value)
            addBSTreeNode(pCurrent->m_pright, value);   
    }
}