每日一练(38) - 从上往下打印二叉树(二叉树的层次遍历)

题目来自剑指Offer

题目：层次遍历二叉树

代码：

#include <iostream>
#include <assert.h>
using namespace std;

const int SIZE = 100;

struct BinaryTreeNode 
{
	char m_nValue;
	BinaryTreeNode* m_pLeft;
	BinaryTreeNode* m_pRight;
};

void LevelOrder(BinaryTreeNode* pRoot)
{
	if (!pRoot)
	{
		cout<<"空树!"<<endl;
		return;
	}

	BinaryTreeNode* Queue[SIZE];
	int nRear = 0;
	int nFront = 0;
	BinaryTreeNode* pNode = NULL;
	
	Queue[nRear++] = pRoot;
	while (nRear != nFront)
	{
		pNode = Queue[(nFront++)%SIZE];
		
		cout<<pNode->m_nValue<<" ";

		if (pNode->m_pLeft)
		{
			Queue[(nRear++)%SIZE] = pNode->m_pLeft;
		}

		if (pNode->m_pRight)
		{
			Queue[(nRear++)%SIZE] = pNode->m_pRight;
		}
	}
}

void Create(BinaryTreeNode*& pRoot)    
{    
	char newData;    
	cin >> newData;    
	if ('#' == newData)    
	{    
		pRoot = NULL;    
	}    
	else    
	{    
		pRoot = new BinaryTreeNode;    
		pRoot->m_nValue = newData;    
		Create(pRoot->m_pLeft);    
		Create(pRoot->m_pRight);     
	}    
}    

int main()
{
	BinaryTreeNode* Root = NULL;
	Create(Root);
	LevelOrder(Root);
	system("pause");
	return 1;
}

注意：

树的输入类似树的子结构，这里不再详述。