编程之美 -求二叉树中节点的最大距离

struct Node
{
	Node* pLeft;	//左子树
	Node* pRight;	//右子树
	int nMaxLeft;	//左子树中的最长距离
	int nMaxRight;	//右子树中的最长距离
	char chValue;	//该节点的值
};

int nMaxLen = 0;

//寻找树中最长的两段距离
void findMaxLen(Node* pRoot)
{
	//遍历到叶子节点，则返回
	if (pRoot == NULL)
	{
		return;
	}

	//如果左子树为空，那么该节点的左边最长距离为0
	if (pRoot->pLeft == NULL)
	{
		pRoot->nMaxLeft = 0;
	}

	//如果右子树为空，那么该节点的右边最长距离为0
	if (pRoot->pRight == NULL)
	{
		pRoot->nMaxRight = 0;
	}
	
	//如果左子树不为空，递归寻找左子树最长距离
	if (pRoot->pLeft != NULL)
	{
		findMaxLen(pRoot->pLeft);
	}
	
	//如果右子树不为空，递归寻找右子树最长距离
	if (pRoot->pRight != NULL)
	{
		findMaxLen(pRoot->pRight);
	}
	
	//计算左子树最长节点距离
	if (pRoot->pLeft != NULL)
	{
		int nTemp;
		if (pRoot->pLeft->nMaxLeft > pRoot->pLeft->nMaxRight)
		{
			nTemp = pRoot->pLeft->nMaxLeft;
		}
		else
			nTemp = pRoot->pLeft->nMaxRight;
		pRoot->nMaxLeft = nTemp+1;
	}
	
	//计算右子树最长节点距离
	if (pRoot->pRight != NULL)
	{
		int nTemp;
		if (pRoot->pRight->nMaxLeft > pRoot->pRight->nMaxRight)
		{
			nTemp = pRoot->pRight->nMaxLeft;
		}
		else
			nTemp = pRoot->pRight->nMaxRight;
		pRoot->nMaxRight = nTemp+1;
	}

	//更新最长距离
	if (pRoot->nMaxLeft+pRoot->nMaxRight > nMaxLen)
	{
		nMaxLen = pRoot->nMaxLeft+pRoot->nMaxRight;
	}

}