经典DFS--找油田---POJ 1562

A B C D E F G H I J K L M N O P Q R S T U V

H - 深搜/广搜 基础
Time Limit:1000MS Memory Limit:10000KB 64bit IO Format:%I64d
& %I64u
Submit Status Practice POJ
1562

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 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

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

//@author:  yzj   Date:2015/07/26
//sourse :  http://acm.hust.edu.cn/vjudge/contest/view.action?cid=82603#problem/H //meaning:  经典找油田DFS问题
#include <iostream>
#include <cstdio>
#include <queue>

using namespace std;
const int  MAXN  = 105;
int n, m;
char c[MAXN][MAXN];

void dfs(int x, int y)
{
c[x][y]='*';
for(int i = -1; i <= 1; i++)
{
for(int j = -1; j <=1; j++)
{
int nx = x+i, ny = y+j;
if(0<=nx&&nx<n&&0<=ny&&ny<m&&c[nx][ny]=='@')
{
dfs(nx, ny);
}
}
}
}

int main()
{
//freopen("f:/yzj/cppCode/input.txt", "r", stdin);
/*
又学到了一个小技巧：由于scanf函数不能自动忽略空格，所以在输入数字紧接着要
输入字符型char时，我们就需要小心了，不要读到空格或是回车
解决方法有两种：
1.使用getchar()函数
2.直接在%d或者是%c前面使用空格，就好了
*/
while(~scanf(" %d %d", &n, &m))
{
if(n == 0 && m==0) break;
//getchar();
for(int i = 0 ; i < n; i++)
{
for(int j = 0; j < m; j++)
{
scanf(" %c", &c[i][j]);
}
//getchar();
}
//        for(int i = 0 ; i < n; i++)
//        {
//            for(int j = 0; j < m; j++)
//            {
//                cout << c[i][j];
//            }
//            cout << endl;
//        }
int ans = 0;
for(int i = 0; i < n; i++)
{
for(int j = 0; j < m; j++)
{
if(c[i][j]=='@')
{
dfs(i, j);
ans++;
}
}
}
printf("%d\n", ans);
}
return 0;
}