travel the binary tree by level( 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( 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

if I rest, I rust.

problem( from <beauty of programming>)

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

eg: the following binary tree

the travelling result follows

my solution

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

void _TravelByLevel(node * T)
{
	queue<node *> Q;
	cout<<"travel start"<<endl;
	if(T != NULL)
	{
		Q.push(T);
		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);
		}
	}
	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);
		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);
		}
	}
	cout<<"travel over"<<endl;

}

void _Visit(node * T)
{
	cout<<T->data<<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( from top to down)