HDU-2952 Counting Sheep （DFS）

Counting Sheep

Time Limit : 2000/1000ms (Java/Other)   Memory Limit : 32768/32768K (Java/Other)

Total Submission(s) : 14   Accepted Submission(s) : 12

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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

2
4 4
#.#.
.#.#
#.##
.#.#
3 5
###.#
..#..
#.###

Sample Output

6
3

Source

IDI Open 2009

 #include <stdio.h>
 #include <string.h>
  char map[][];
 int f[][] = {,,-,,,,,-}; //注意定义方向数组。只有四个方向上下左右。
 int n,m,s;
 void dfs(int x,int y)
 {
     int i;
     int x1,y1;
     for(i = ;i<;i++)
     {
         x1= x+f[i][];
         y1 = y+f[i][];
         if(x1< || y1< || x1>=n || y1>=m || map[x1][y1]!='#')
         continue;
         map[x1][y1] = '.';
         dfs(x1,y1);
     }
 } 

 int main()
 {
     int t;
     scanf("%d",&t);
     while(t--)
     {
         scanf("%d%d",&n,&m);
         int i,j,l;
         s = ;
         for(i = ;i<n;i++)
         {
             scanf("%s",map[i]);
         }
         for(i = ;i<n;i++)
         {
             for(j = ;j<m;j++)
             {
                 if(map[i][j] == '#')
                 {
                     s++;
                     map[i][j] = '.';
                     dfs(i,j);
                 }
             }
         }
         printf("%d\n",s);
     } 

     return ;
 }