二叉树中最远的两个结点的距离

struct BinTreeNode
{
int _data;
BinTreeNode* _left;
BinTreeNode* _right;
BinTreeNode(int data = 0) :_data(data), _left(NULL), _right(NULL)
{}
};

int DepthBin(BinTreeNode* root)
{
if (root == NULL)
return 0;
int left = DepthBin(root->_left);
int right = DepthBin(root->_right);
return left > right ? left + 1 : right + 1;
}

void FindMaxLenOfBinTree(BinTreeNode* root, int& maxPath)
{
if (root == NULL)
return;
int leftDepth = DepthBin(root->_left);
int rightDepth = DepthBin(root->_right);
if (maxPath < leftDepth + rightDepth)
{
maxPath = leftDepth + rightDepth;
}
FarestRoot(root->_left, maxPath);
FarestRoot(root->_right, maxPath);
}

int FindMaxLen(BinTreeNode* root)
{
int maxPath = 0;
FarestRoot(root, maxPath);
return maxPath;
}

struct BinTreeNode
{
int _data;
int _maxLeft;
int _maxRight;
BinTreeNode* _left;
BinTreeNode* _right;
BinTreeNode(int data = 0)
:_data(data), _maxLeft(0), _maxRight(0)
,_left(NULL), _right(NULL)
{}
};

void FindMaxLenOfBinTree(BinTreeNode* root, int& maxLen)
{
if (root == NULL)
return;

//左子树为空，该节点的左边最长距离为0
if (root->_left == NULL)
{
root->_maxLeft = 0;
}
//右子树为空，该节点的右边最长距离为0
if (root->_right == NULL)
{
root->_maxRight = 0;
}
if (root->_left != NULL)
{
FindMaxLenOfBinTree(root->_left, maxLen);
}
if (root->_right != NULL)
{
FindMaxLenOfBinTree(root->_right, maxLen);
}
if (root->_left != NULL)
{
int tmp = 0;
if (root->_left->_maxLeft > root->_left->_maxRight)
{
tmp = root->_left->_maxLeft;
}
else
{
tmp = root->_left->_maxRight;
}
root->_maxLeft = tmp + 1;
}
if (root->_right != NULL)
{
int tmp = 0;
if (root->_right->_maxLeft > root->_right->_maxRight)
{
tmp = root->_right->_maxLeft;
}
else
{
tmp = root->_right->_maxRight;
}
root->_maxRight = tmp + 1;
}
if (root->_maxLeft + root->_maxRight > maxLen)
{
maxLen = root->_maxLeft + root->_maxRight;
}
}

int FindMaxLen(BinTreeNode* root)
{
int maxLen = 0;
FindMaxLenOfBinTree(root, maxLen);
return maxLen;
}