面试题：判断一个节点是否在一棵二叉树中

题目：判断一个节点是否在一棵二叉树中
结点定义如下

struct BinaryTree{    BinaryTree(char data)    :_pLeft(NULL)    , _pRight(NULL)    , _data(data)    {}    BinaryTree *_pLeft;    BinaryTree *_pRight;    char _data;};

首先附上创建树代码

void CreateBinaryTree(BinaryTree *&pRoot, char *str,size_t size, size_t &index){    if (index < size && str[index] != '#')    {        pRoot = new BinaryTree(str[index]);        CreateBinaryTree(pRoot->_pLeft, str, size, ++index);        CreateBinaryTree(pRoot->_pRight, str, size, ++index);    }}

思路：判断当前结点与查找的结点是否相等，如果不相等寻找左子树，继而寻找右子树，这样用递归很容易实现

• 代码实现

bool IsNodeInTree(BinaryTree *pRoot,BinaryTree *pNode){    if (NULL == pRoot || NULL == pNode)        return false;    if (pRoot->_data == pNode->_data)        return true;    if (IsNodeInTree(pRoot->_pLeft, pNode) || IsNodeInTree(pRoot->_pRight, pNode))        return true;        return false;}

• 测试用例

void funtest(){     BinaryTree *pRoot;    char *str = "abdh###e##cf##g#i";    size_t index = 0;    CreateBinaryTree(pRoot, str, strlen(str), index);    BinaryTree *node = pRoot->_pLeft;    cout << node->_data << " ";    bool ret = IsNodeInTree(pRoot, node);    cout << ret << endl;    node = pRoot->_pLeft->_pLeft;    cout << node->_data << " ";    ret = IsNodeInTree(pRoot, node);    cout << ret << endl;    node = pRoot->_pLeft->_pLeft;    cout << node->_data << " ";    ret = IsNodeInTree(pRoot, node);    cout << ret << endl;    node = pRoot->_pLeft->_pRight;    cout << node->_data << " ";    ret = IsNodeInTree(pRoot, node);    cout << ret << endl;    node = pRoot->_pRight;    cout << node->_data << " ";    ret = IsNodeInTree(pRoot, node);    cout << ret << endl;    node = pRoot->_pRight->_pLeft;    cout << node->_data << " ";    ret = IsNodeInTree(pRoot, node);    cout << ret << endl;    node = pRoot->_pRight->_pRight;    cout << node->_data << " ";    ret = IsNodeInTree(pRoot, node);    cout << ret << endl;    node = pRoot->_pRight->_pRight->_pRight;    cout << node->_data << " ";    ret = IsNodeInTree(pRoot, node);    cout << ret << endl;    node = new BinaryTree('n');    cout << node->_data << " ";    ret = IsNodeInTree(pRoot, node);    cout << ret << endl;    node = new BinaryTree('e');    cout << node->_data << " ";    ret = IsNodeInTree(pRoot, node);    cout << ret << endl;    ret = IsNodeInTree(pRoot, NULL);    cout << ret << endl;}