广度优先搜索 codevs 2806 红与黑

 1 /*比较简单的广搜题目*/
 2 #include<iostream>
 3 using namespace std;
 4 #include<cstdio>
 5 #include<cstring>
 6 #include<queue>
 7 int w,h;
 8 int jz[25][25]={0};
 9 struct poi{
10     int x,y;
11 };
12 int xq,yq;
13 int xx[]={1,-1,0,0};
14 int yy[]={0,0,1,-1};
15 void input()
16 {
17     char s[25];
18     for(int i=1;i<=h;++i)
19     {
20         scanf("%s",s+1);
21         for(int j=1;j<=w;++j)
22         {
23             if(s[j]==‘#‘)
24               jz[i][j]=1;
25             if(s[j]==‘@‘)
26             {
27                 xq=i;yq=j;
28             }
29         }
30     }
31 }
32 int bfs()
33 {
34     int ans=0;
35     poi p;
36     p.x=xq;p.y=yq;
37     queue<poi>que;
38     que.push(p);
39     while(!que.empty())
40     {
41         poi k=que.front();
42         que.pop();
43         int x=k.x,y=k.y;
44         jz[x][y]=2;
45         for(int i=0;i<4;++i)
46         {
47             int x1=x+xx[i],y1=y+yy[i];
48             if(x1>=1&x1<=h&y1>=1&&y1<=w&&jz[x1][y1]==0)
49             {
50                 que.push(poi{x1,y1});
51             }
52         }
53     }
54     for(int i=1;i<=h;++i)
55       for(int j=1;j<=w;++j)
56       if(jz[i][j]==2) ans++;
57     return ans;
58 }
59 int main()
60 {
61     while(scanf("%d%d",&w,&h)==2)
62     {
63         if(w==0&&h==0) break;
64         memset(jz,0,sizeof(jz));
65         input();
66         printf("%d\n",bfs());
67     }
68     return 0;
69 }