HDU 2952 Counting Sheep(DFS)

题目链接

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

题解：题目描述什么的一大段废话，直接看输入输出，发现是一个经典的DFS连通块问题。

#include <cstdio>
#include <iostream>
#include <string>
#include <sstream>
#include <cstring>
#include <stack>
#include <queue>
#include <algorithm>
#include <cmath>
#include <map>
#define ms(a) memset(a,0,sizeof(a))
#define msp memset(mp,0,sizeof(mp))
#define msv memset(vis,0,sizeof(vis))
using namespace std;
//#define LOCAL
char mp[][];
int n,m;
int ans;
int dir[][]={{,},{,-},{,},{-,}};
void dfs(int x,int y)
{
    for(int i=;i<;i++)
    {
        int nx=x+dir[i][],ny=y+dir[i][];
        if(nx>=&&nx<n&&ny>=&&ny<m)
        {
            if(mp[nx][ny]=='#')
            {
                mp[nx][ny]='.';
                dfs(nx,ny);
            }
        }
    }
    return;
}
int main()
{
#ifdef LOCAL
    freopen("in.txt", "r", stdin);
#endif // LOCAL
    //Start
    int N;
    cin>>N;
    while(N--)
    {
        cin>>n>>m;
        msp,ans=;
        for(int i=; i<n; i++)cin>>mp[i];
        for(int i=; i<n; i++)
        for(int j=; j<m; j++)
        if(mp[i][j]=='#')
        {
            mp[i][j]='.';
            ans++;
            dfs(i,j);
        }
        printf("%d\n",ans);
    }
    return ;
}