算法系列之图--BFS

 1 #include <iostream>
 2 #include <list>
 3 #include <queue>
 4 using namespace std;
 5 
 6 //无向图
 7 class Graph{
 8 private:
 9     int v;//图的节点数
10     list<int> *adj;//指向包含临接链表的数组
11 public:
12     Graph(int v);
13     void addEdge(int start,int end);//添加临接边
14     void BFS(int s);//广度优先搜索
15 };
16 
17 Graph::Graph(int v){
18     this->v = v;
19     adj = new list<int>[v];
20 }
21 
22 //无向图中添加一条边在临接表中添加两项
23 void Graph::addEdge(int start,int end){
24     adj[start].push_back(end);
25     adj[end].push_back(start);
26 }
27 
28 void Graph::BFS(int s){
29     //先标记所有结点都未被访问
30     bool* visited = new bool[v];
31     for (int i=0;i<v;i++)
32         visited[i] = false;
33     //创建队列
34     queue<int> q = queue<int>();
35     //先设置源结点
36     visited[s] = true;
37     q.push(s);
38 
39     while(!q.empty()){
40         int node = q.front();
41         cout<<node<<" ";
42         q.pop();
43         //node结点的临接表
44         list<int> nlist = adj[node];
45         list<int>::iterator beg = nlist.begin();
46         for (;beg != nlist.end();beg++){            
47             if (!visited[*beg]){
48                 visited[*beg] = true;
49                 q.push(*beg);
50             }
51         }
52     }
53     cout<<"\n";
54 }
55 
56 int main(){
57     Graph g = Graph(6);
58     g.addEdge(0,1);
59     g.addEdge(0,2);
60     g.addEdge(0,5);
61     g.addEdge(1,3);
62     g.addEdge(2,3);
63     g.addEdge(2,5);
64     g.addEdge(2,4);
65     g.addEdge(4,5);
66     g.BFS(0);
67 
68     return 0;
69 }