travel the binary tree by level 2 ( from top to down )

个人信息：就读于燕大本科软件工程专业 目前大三;

本人博客：google搜索“cqs_2012”即可;

个人爱好：酷爱数据结构和算法，希望将来从事算法工作为人民作出自己的贡献;

博客内容：travel the binary tree by level 2 ( from top to down );

博客时间：2014-5-3;

编程语言：C++ ;

编程坏境：Windows 7 专业版 x64;

编程工具：vs2008 32位编译器;

制图工具：office 2010 ppt;

硬件信息：7G-3 笔记本;

my words

compute is so good and so funny.

problem

travel the binary tree by level( from top to down ), and class it by level.

eg: the binary tree follows

travelling result follows

my solution

solve this problem by queue, visit every node while it  be popped and push its children while it has and class it by level.

function follow

void _TravelByLevel(node * T)
{
	queue<node *> Q;
	cout<<"travel start"<<endl;
	if(T != NULL)
	{
		Q.push(T);
		Q.push(NULL);
		node * p;
		while(! Q.empty())
		{
			// first action
			p = Q.front();
			Q.pop();
			_Visit(p);
			// second action
			if(p->left != NULL)
				Q.push(p->left);
			if(p->right != NULL)
				Q.push(p->right);
			// third action
			if(Q.front() == NULL)
			{
				Q.pop();
				if(Q.empty())
					break;
				Q.push(NULL);
				cout<<"level"<<endl;
			}
		}
	}
	cout<<"travel over"<<endl;

}

my code

test.cpp

#include<iostream>
#include<queue>
using namespace std;

class node
{
public:
    int data ;
    node * left ;
    node * right ;
    node()
	{
        data = 0 ;
        left = right = NULL ;
    }
};

void _MakeTree(node * &T,int *data,int length);
void _Insert(node * & T,int data);
void _Visit(node * T);
void _TravelByLevel(node * T);

void _MakeTree(node * &T,int *data,int length)
{
    for(int i=0;i<length;i++)
    {
		_Insert(T,data[i]);
    }
}

void _Insert(node * & T,int data)
{
    if(T == NULL)
    {
		T = new node();
		T -> data = data;
    }
    else
    {
		node * p = T;
		while(p != NULL)
		{
			if(data == p->data )
			break;
			else if(data < p->data )
			{
				if(p->left != NULL)
				{
					p = p ->left;
				}
				else{
					p->left = new node();
					(p->left) ->data = data;
					break;
				}
			}
			else{
				if(p->right != NULL)
					p = p->right;
				else{
					p->right = new node() ;
					(p->right) ->data = data ;
					break ;
				}
			}
		}
    }
}

void _TravelByLevel(node * T)
{
	queue<node *> Q;
	cout<<"travel start"<<endl;
	if(T != NULL)
	{
		Q.push(T);
		Q.push(NULL);
		node * p;
		while(! Q.empty())
		{
			// first action
			p = Q.front();
			Q.pop();
			_Visit(p);
			// second action
			if(p->left != NULL)
				Q.push(p->left);
			if(p->right != NULL)
				Q.push(p->right);
			// third action
			if(Q.front() == NULL)
			{
				Q.pop();
				if(Q.empty())
					break;
				Q.push(NULL);
				cout<<"level"<<endl;
			}
		}
	}
	cout<<"travel over"<<endl;

}

void _Visit(node * T)
{
	if(T != NULL)
		cout<<T->data<<endl;
	else cout<<"visit NULL"<<endl;
}

int main()
{
    int data[] = {8,6,3,7,2,1,13,12,15,17};

    node * T = NULL;
    _MakeTree(T,data,10);
	_TravelByLevel(T);
    system("pause");
    return 0;
}

travel the binary tree by level 2 ( from top to down )