zoj1709 poj1562

Oil Deposits

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Time Limit: 2 Seconds      Memory Limit: 65536 KB

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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

#include <cstdio>

char grid[101][101];    //存储网格
int m, n;                //网格的大小，即行和列
//一个方格的八个相邻方向
int dir[8][2] = { {-1,-1}, {-1,0}, {-1,1}, {0,1}, {1,1}, {1,0}, {1,-1}, {0,-1} };

void DFS( int x, int y )    //从(x,y)位置进行深度优先搜索
{
    int i, xx, yy;
    grid[x][y] = '*'; //将grid[x][y]由@设置成*，保证不会再遍历这个方格了
    for( i=0; i<8; i++ )
    {
        xx = x + dir[i][0];  yy = y + dir[i][1];
        if( xx<0 || yy<0 || xx>=m || yy>=n )  continue;
        if( grid[xx][yy] == '@' ) //如果相邻方格还是@，则继续搜索
            DFS(xx, yy);
    }
}

int main( )
{
    int i, j;    //循环变量
    int count;    //对每个网格，统计得到的油田数目
    while( 1 )
    {
        scanf( "%d%d", &m, &n );
        if( m==0 )  break;
        for( i=0; i<m; i++ )  scanf( "%s", grid[i] );
        count = 0;
        for( i=0; i<m; i++ )
        {
            for( j=0; j<n; j++ )
            {
                if( grid[i][j]=='@' )
                {
                    DFS(i,j);    //从(i,j)位置进行DFS搜索
                    count++;
                }
            }
        }
        printf( "%d
", count );
    }
    return 0;
}