#include <iostream>

 #include <list>

 #include <queue>

 using namespace std;

 //无向图

 class Graph{

 private:

     int v;//图的节点数

     list<int> *adj;//指向包含临接链表的数组

 public:

     Graph(int v);

     void addEdge(int start,int end);//添加临接边

     void BFS(int s);//广度优先搜索

 };

 Graph::Graph(int v){

     this->v = v;

     adj = new list<int>[v];

 }

 //无向图中添加一条边在临接表中添加两项

 void Graph::addEdge(int start,int end){

     adj[start].push_back(end);

     adj[end].push_back(start);

 }

 void Graph::BFS(int s){

     //先标记所有结点都未被访问

     bool* visited = new bool[v];

     for (int i=;i<v;i++)

         visited[i] = false;

     //创建队列

     queue<int> q = queue<int>();

     //先设置源结点

     visited[s] = true;

     q.push(s);

     while(!q.empty()){

         int node = q.front();

         cout<<node<<" ";

         q.pop();

         //node结点的临接表

         list<int> nlist = adj[node];

         list<int>::iterator beg = nlist.begin();

         for (;beg != nlist.end();beg++){

             if (!visited[*beg]){

                 visited[*beg] = true;

                 q.push(*beg);

             }

         }

     }

     cout<<"\n";

 }

 int main(){

     Graph g = Graph();

     g.addEdge(,);

     g.addEdge(,);

     g.addEdge(,);

     g.addEdge(,);

     g.addEdge(,);

     g.addEdge(,);

     g.addEdge(,);

     g.addEdge(,);

     g.BFS();

     return ;

 }