从上到下打印二叉树（层序遍历，广度优先遍历二叉树）

//从上往下打印二叉树（层序遍历，广度优先遍历）
#include<stdio.h>
#include<queue>
using namespace std;

struct BinaryTreeNode
{
	int m_nValue;
	BinaryTreeNode* m_pLef;
	BinaryTreeNode* m_pRight;
};

BinaryTreeNode* createBinaryTreeNode(int value)
{
	BinaryTreeNode* pNode = new BinaryTreeNode();
	pNode->m_nValue = value;
	pNode->m_pLef = NULL;
	pNode->m_pRight = NULL;
	return pNode;
}
void connectBinaryTreeNode(BinaryTreeNode* pParent, BinaryTreeNode* pLeftChild,
						   BinaryTreeNode* pRightChild)
{
	if(!pParent || !pLeftChild || !pRightChild)
		return;

	pParent->m_pLef = pLeftChild;
	pParent->m_pRight = pRightChild;
}

void printTreeFromTopToBottom(BinaryTreeNode* pRoot)
{
	if(pRoot == NULL)
		return;
	queue<BinaryTreeNode*> btnQueue;
	btnQueue.push(pRoot);
	while(!btnQueue.empty())
	{
		BinaryTreeNode* pTemp = btnQueue.front();
		btnQueue.pop();
		printf("%d\t",pTemp->m_nValue);
		if(pTemp->m_pLef)
			btnQueue.push(pTemp->m_pLef);
		if(pTemp->m_pRight)
			btnQueue.push(pTemp->m_pRight);
	}
}
void test()
{
	BinaryTreeNode* pNode1 = createBinaryTreeNode(8);
	BinaryTreeNode* pNode2 = createBinaryTreeNode(6);
	BinaryTreeNode* pNode3 = createBinaryTreeNode(10);
	BinaryTreeNode* pNode4 = createBinaryTreeNode(5);
	BinaryTreeNode* pNode5 = createBinaryTreeNode(7);
	BinaryTreeNode* pNode6 = createBinaryTreeNode(9);
	BinaryTreeNode* pNode7 = createBinaryTreeNode(11);

	connectBinaryTreeNode(pNode1,pNode2,pNode3);
	connectBinaryTreeNode(pNode2,pNode4,pNode5);
	connectBinaryTreeNode(pNode3,pNode6,pNode7);

	printTreeFromTopToBottom(pNode1);
}
int main()
{
	test();
	return 0;
}

注意图的广度优先遍历