Counting Sheep(HDU2952、广搜)

本文介绍了一种通过广度优先搜索算法来计算二维网格中相连羊群数量的方法。该算法用于帮助解决睡前数羊的问题,通过计算网格上相连的羊('#'字符)形成的不同群体数量。

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Counting Sheep

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

题意:计算#相邻的块数,只算前后左右。
思路:广搜
代码:
#include<stdio.h>
#include<queue>
#include<string.h>
using namespace std;
struct zuobiao
{
    int x,y;
} now,nex;
char a[122][122];
int vis[121][121];
int fx[4]= {0,0,-1,1};
int fy[4]= {-1,1,0,0};
int output;
int n,m;
void bfs(int x,int y)
{
    output++;
    now.x=x;
    now.y=y;
    queue<zuobiao>s;
    s.push(now);
    vis[x][y]=1;
    while(!s.empty())
    {
        now=s.front();
        s.pop();
        for(int i=0; i<4; i++)
        {
            nex.x=now.x+fx[i];
            nex.y=now.y+fy[i];
            if(nex.x>=1&&nex.x<=n&&nex.y>=1&&nex.y<=m&&a[nex.x][nex.y]=='#'&&vis[nex.x][nex.y]==0)
            {
                vis[nex.x][nex.y]=1;
                s.push(nex);
            }
        }
    }
}
int main()
{
    int t;
    scanf("%d",&t);
    while(t--)
    {
        memset(vis,0,sizeof(vis));
        scanf("%d%d",&n,&m);
        for(int i=1; i<=n; i++)
        scanf("%s",a[i]+1);
        output=0;
        for(int i=1; i<=n; i++)
        {
            for(int j=1; j<=m; j++)
            {
                if(a[i][j]=='#'&&vis[i][j]==0)//如果当前是#,并且这个点没有和别的#连通过。进入bfs
                {
                    bfs(i,j);
                }
            }
        }
        printf("%d\n",output);
    }
}
 

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