分行从上到下打印二叉树

#include<iostream>
#include<deque>

using namespace std;
struct BinaryTreeNode
{
	int                 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);
	}
}
//分行从上到下打印
void Print(BinaryTreeNode* pRoot)
{
	if (pRoot == nullptr)
		return;
//toBePrinted保存当前行的打印数，nextLevel保存下一行的打印数
	int toBePrinted = 1;
	int nextLevel = 0;
//创建一个队列，队列首元素是当前要打印的元素
	deque<BinaryTreeNode*> dequeTreeNode;
	dequeTreeNode.push_back(pRoot);
//当队列不为空时，循环继续
	while (dequeTreeNode.size())
	{
//打印队列首元素，同时把左结点和右结点按顺序压入队列中，同时++nextLevel
		BinaryTreeNode* pNode = dequeTreeNode.front();
		printf("%d  ", pNode->m_dbValue);
		if (pNode->m_pLeft!=nullptr)
		{
			dequeTreeNode.push_back(pNode->m_pLeft);
			++nextLevel;
		}
		if (pNode->m_pRight != nullptr)
		{
			dequeTreeNode.push_back(pNode->m_pRight);
			++nextLevel;
		}
		dequeTreeNode.pop_front();
		--toBePrinted;
//当toBePrint为0时表示当前行已全部打印完，打印换行符并把nextLevel赋值给toBePrinted
		if (toBePrinted == 0)
		{
			printf("\n");
			toBePrinted = nextLevel;
			nextLevel = 0;
		}
	}
}

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);

	Print(pNode10);

	DestroyTree(pNode10);

	return 0;
}