經典DFS--找油田---POJ 1562

原創

bmxklYzj

2020-07-02 10:24

H - 深搜/廣搜基礎

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

//@author:  yzj   Date:2015/07/26
//sourse :  http://acm.hust.edu.cn/vjudge/contest/view.action?cid=82603#problem/H
//meaning:  經典找油田DFS問題
#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);
    /*
    又學到了一個小技巧：由於scanf函數不能自動忽略空格，所以在輸入數字緊接着要
    輸入字符型char時，我們就需要小心了，不要讀到空格或是回車
    解決方法有兩種：
            1.使用getchar()函數
            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;
}