Oil Deposits

原题链接：http://acm.hdu.edu.cn/showproblem.php?pid=1241

Problem Description：

The GeoSurvComp geologic survey company is responsible for detecting underground oil deposits. GeoSurvComp works with one large rectangular region of land at a time, and creates a grid that divides the land into numerous square plots. It then analyzes each plot separately, using sensing equipment to determine whether or not the plot contains oil. A plot containing oil is called a pocket. If two pockets are adjacent, then they are part of the same oil deposit. Oil deposits can be quite large and may contain numerous pockets. Your job is to determine how many different oil deposits are contained in a grid.

Input：

The input file contains one or more grids. Each grid begins with a line containing m and n, the number of rows and columns in the grid, separated by a single space. If m = 0 it signals the end of the input; otherwise 1 <= m <= 100 and 1 <= n <= 100. Following this are m lines of n characters each (not counting the end-of-line characters). Each character corresponds to one plot, and is either '*', representing the absence of oil, or '@', representing an oil pocket.

Output：

For each grid, output the number of distinct oil deposits. Two different pockets are part of the same oil deposit if they are adjacent horizontally, vertically, or diagonally. An oil deposit will not contain more than 100 pockets.

Sample Input：

1 1
*
3 5
*@*@*
**@**
*@*@*
1 8
@@****@*
5 5
****@
*@@*@
*@**@
@@@*@
@@**@
0 0

Sample Output：

0
1
2
2

解题思路：

dfs，将搜过的油田填上

AC代码：

#include<iostream>
#include<stdio.h>
using namespace std;

char grid[110][110];                                    //定义油田数组
int n, m;						//主副函数都要使用

int p(int i, int j)					//判断数组是否越界
{
	if (i < 0 || i >= n || j < 0 || j >= m)				
		return 0;
	else
		return 1;
}
int check(int x, int y)
{
	grid[x][y] = '*';				//判断周围八个格子是否为油
	for (int dx = -1; dx <= 1; ++dx)
	{
		for (int dy = -1; dy <= 1; ++dy)
		{
			if (grid[x + dx][y + dy] == '@' &&  p(x + dx,y + dy)==1 )
				check(x + dx, y + dy);
		}
	}
	return 0;
	
}
int main ( )
{	
	while ( cin>>n>>m )
	{
		int sum = 0;
		if (n == 0 && m == 0)		
			break;				//n和m都等于0时输入结束

		for (int i = 0; i < n; i++) 
		{
			for (int j = 0; j < m; j++)
			{
				cin >> grid[i][j];	//将油田网格输入grid
			}
		}

		for (int i = 0; i < n; i++)
		{
			for (int j = 0; j < m; j++)	//遍历grid数组
			{
				if (grid[i][j] == '@')	//判断是否为油
				{
					check(i, j);	//是油进行检查周围的油田网格
					sum++;
				}
			}
		}
		cout << sum<<endl;
	}
	return 0;
}