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ACM HDU-2952 Counting Sheep A while ago I had trouble sleeping

 

Counting Sheep

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 2060    Accepted Submission(s): 1359

Problem Description
A while ago I had trouble sleeping. I used to lie awake, staring at the ceiling, for hours and hours. Then one day my grandmother suggested I tried counting sheep after I‘d gone to bed. As always when my grandmother suggests things, I decided to try it out. The only problem was, there were no sheep around to be counted when I went to bed.
Creative as I am, that wasn‘t going to stop me. I sat down and wrote a computer program that made a grid of characters, where # represents a sheep, while . is grass (or whatever you like, just not sheep). To make the counting a little more interesting, I also decided I wanted to count flocks of sheep instead of single sheep. Two sheep are in the same flock if they share a common side (up, down, right or left). Also, if sheep A is in the same flock as sheep B, and sheep B is in the same flock as sheep C, then sheeps A and C are in the same flock.
Now, I‘ve got a new problem. Though counting these sheep actually helps me fall asleep, I find that it is extremely boring. To solve this, I‘ve decided I need another computer program that does the counting for me. Then I‘ll be able to just start both these programs before I go to bed, and I‘ll sleep tight until the morning without any disturbances. I need you to write this program for me.
 
Input
The first line of input contains a single number T, the number of test cases to follow.
Each test case begins with a line containing two numbers, H and W, the height and width of the sheep grid. Then follows H lines, each containing W characters (either # or .), describing that part of the grid.
 
Output
For each test case, output a line containing a single number, the amount of sheep flock son that grid according to the rules stated in the problem description.
Notes and Constraints 0 < T <= 100 0 < H,W <= 100
 
Sample Input
24 4
#.#.
.#.#
#.##
.#.#
3 5
###.#
..#..
#.###
 
Sample Output
6
3
 
题目来源:http://acm.hdu.edu.cn/showproblem.php?pid=2952
 
值得注意的是:bfs()函数里面定义的参数一定要定义成全局变量,如果用C语言的scanf来输入数据,要用getchar()来清除缓存区的‘\n‘。
 
 1 #include<iostream> 2 using namespace std; 3  4 int arr[4][2]={0,1,1,0,0,-1,-1,0};    //分四个方向搜索  5 char sheep[101][101]; 6 int T,i,j,sum,h,w; 7  8 //搜索羊群  9 void bfs(int a,int b)10 {11     if(sheep[a][b]==.)    return;            //遇到 ‘.‘返回 12     if(a<0||b<0||a>=h||b>=w)    return;        //数组越界返回 13     sheep[a][b]=.;                        //记录,将每次找到的羊群变成‘.‘,下次循环直接跳过 14     for(int i=0;i<4;i++)15         bfs(a+arr[i][0],b+arr[i][1]);        //找到每只羊以后向四个方向搜索 16 }17 18 int main()19 {    20     cin>>T;21     while(T--)22     {23         cin>>h>>w;24         for(i=0;i<h;i++)25             for(j=0;j<w;j++)26                  cin>>sheep[i][j];        //此处利用c++的输入方法,不用考虑缓冲区换行符的影响 27         sum=0;28         for(i=0;i<h;i++)29             for(j=0;j<w;j++)30             {31                 if(sheep[i][j]==#)32                 {33                     ++sum;                //用sum来记录每次找到的羊群数量 34                     bfs(i,j);35                 }36             }37         cout<<sum<<endl;38     }39     return 0;40 }