DS树--二叉树高度

#include <iostream>
#include <string>
using namespace std;
class BiTreeNode {
public:
    char  data;					//数据域
    BiTreeNode  *leftChild,  *rightChild;	//左右子树指针
    BiTreeNode():leftChild(NULL), rightChild(NULL){}
    ~BiTreeNode() {}
};

class BiTree {
private:
    BiTreeNode *root;	//根结点指针
    string sTree;		//建树字符串
    int pos;			//标识建树字符串的当前字符位置
    BiTreeNode * CreateTree();//建树私有函数
public:
    BiTree():root(NULL) {};
    void Create(string vArray);	//建树公有接口，参数是特定的先序遍历字符串
    int CountHeight(BiTreeNode*T) {
        if(T==NULL)
            return 0;
        return max(CountHeight(T->leftChild), CountHeight(T->rightChild))+1;
    }
    void Show(){
        cout << CountHeight(root) << endl;
    }
};
void BiTree::Create(string vArray)
{	pos=0;
    sTree.assign(vArray);	//把参数保存到内部字符串
    root = CreateTree();	//建树成功后root指向根结点
}
BiTreeNode* BiTree::CreateTree() {
    if(pos==sTree.size()||sTree[pos]=='0'){
        pos++;
        return NULL;
    }
    BiTreeNode*T=new BiTreeNode();
    T->data=sTree[pos++];
    T->leftChild=CreateTree();
    T->rightChild=CreateTree();
    return T;
}
int main()
{	int t;
    string vArray;
    cin>>t;
    while(t--)
    {	cin>>vArray;
        BiTree myTree;
        myTree.Create(vArray);
        myTree.Show();
    }
    return 0;
}