HDOJ 1241 Oil Deposits(dfs)

Oil Deposits

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 18204    Accepted Submission(s): 10495

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

0122

 

 

题意：有一片区域，*表示空地，@表示油田，相邻的@都是同一片油田，给出一图形，求有几片油田。

 

真是跪了，开始用mark数组标记同一片油田中的@,却不小心将数组名写错了，找了两个小时。。。

 

题解：dfs的常见题型。

 

代码如下：

 

#include<cstdio>#include<cstring>int n,m;char str[105][105];int dir[8][2]={{1,0},{1,-1},{1,1},{0,-1},{0,1},{-1,-1},{-1,1},{-1,0}};void dfs(int x,int y){int i,dx,dy; for(i=0;i<8;i++) { dx=x+dir[i][0];  dy=y+dir[i][1]; if(dx>=0 && dx<n && dy>=0 && dy<m && str[dx][dy]=='@' ) { str[dx][dy]='*'; dfs(dx,dy); } }}int main(){int i,j;while(scanf("%d%d",&n,&m)&&n||m){    int count=0;for(i=0;i<n;i++)    scanf("%s",str[i]);     for(i=0;i<n;i++)    {    for(j=0;j<m;j++)    {    if(str[i][j]=='@')    {    ++count;    dfs(i,j);    }    }    }    printf("%d\n",count);}return 0;}