从上到下打印二叉树

#include<iostream>
#include<deque>

using namespace std;
struct BinaryTreeNode
{
	double                 m_dbValue;
	BinaryTreeNode*        m_pLeft;
	BinaryTreeNode*        m_pRight;
};
//创建树节点
BinaryTreeNode* CreateBinaryTreeNode(double dbValue)
{
	BinaryTreeNode* pNode = new BinaryTreeNode();
	pNode->m_dbValue = dbValue;
	pNode->m_pLeft = nullptr;
	pNode->m_pRight = nullptr;

	return pNode;
}
//连接结点
void ConnectTreeNodes(BinaryTreeNode* pParent, BinaryTreeNode* pLeft, BinaryTreeNode* pRight)
{
	if (pParent != nullptr)
	{
		pParent->m_pLeft = pLeft;
		pParent->m_pRight = pRight;
	}
}
//释放内存
void DestroyTree(BinaryTreeNode* pRoot)
{
	if (pRoot != nullptr)
	{
		BinaryTreeNode* pLeft = pRoot->m_pLeft;
		BinaryTreeNode* pRight = pRoot->m_pRight;

		delete pRoot;
		pRoot = nullptr;

		DestroyTree(pLeft);
		DestroyTree(pRight);
	}
}
//从上到下按层打印
void PrintFromTopToBottom(BinaryTreeNode* pRoot)
{
	if (pRoot == nullptr)
		return;
//建立一个队列存储要打印的值
	std::deque<BinaryTreeNode*> dequeTreeNode;
	dequeTreeNode.push_back(pRoot);
//当队列不为空时，循环继续
	while (dequeTreeNode.size())
	{
//保存队列头的第一个结点并打印，同时把它弹出
		BinaryTreeNode* pNode = dequeTreeNode.front();
		dequeTreeNode.pop_front();
		printf("%f\n", pNode->m_dbValue);
//先左结点后右结点判断有没有，有则压入队列
		if (pNode->m_pLeft)
			dequeTreeNode.push_back(pNode->m_pLeft);
		if (pNode->m_pRight)
			dequeTreeNode.push_back(pNode->m_pRight);
	}
}

int main()
{
	BinaryTreeNode* pNode10 = CreateBinaryTreeNode(10);
	BinaryTreeNode* pNode6 = CreateBinaryTreeNode(6);
	BinaryTreeNode* pNode14 = CreateBinaryTreeNode(14);
	BinaryTreeNode* pNode4 = CreateBinaryTreeNode(4);
	BinaryTreeNode* pNode8 = CreateBinaryTreeNode(8);
	BinaryTreeNode* pNode12 = CreateBinaryTreeNode(12);
	BinaryTreeNode* pNode16 = CreateBinaryTreeNode(16);

	ConnectTreeNodes(pNode10, pNode6, pNode14);
	ConnectTreeNodes(pNode6, pNode4, pNode8);
	ConnectTreeNodes(pNode14, pNode12, pNode16);

	PrintFromTopToBottom(pNode10);

	DestroyTree(pNode10);

	return 0;
}