POJ -1562 Oil Deposits（BFS）

原创于 2019-08-16 17:12:46 发布 · 519 阅读

1 ·

CC 4.0 BY-SA版权

2018暑假ACM集训同时被 2 个专栏收录

128 篇文章

订阅专栏

ACM_搜索

12 篇文章

订阅专栏

本文介绍了一种使用广度优先搜索(BFS)算法来检测和计数网格中油藏沉积物的方法。通过创建一个网格，将土地划分为多个正方形地块，并使用传感设备确定每个地块是否含有石油。算法的目标是确定不同油藏的数量，其中相邻的油池被视为同一油藏的一部分。该算法适用于大型油藏，可能包含多个油池。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

Oil Deposits

Time Limit: 1000MS	Memory Limit: 10000K

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

bfs入门吧
用结构体存坐标更好(●’◡’●)

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <string.h>
#include <queue>
using namespace std;

char mm[105][105];
int vis[105][105], n, m, ans;
int dir[8][2]={{1,0},{1,1},{1,-1},{0,1},{0,-1},{-1,0},{-1,1},{-1,-1}};

void bfs(int x, int y)
{
    queue<int>a;
    a.push(x);
    a.push(y);
    while(!a.empty())
    {
        int x, y;
        x=a.front();
        a.pop();
        y=a.front();
        a.pop();
        if(vis[x][y]==1)
            continue;
        vis[x][y]=1;
        for(int i=0; i<8; i++)
        {
            int nx, ny;
            nx=x+dir[i][0];
            ny=y+dir[i][1];
            if(ny<1||ny>m||nx<1||nx>n ||vis[nx][ny]==1||mm[nx][ny]=='*')//越界或非油田
                continue;
            a.push(nx);
            a.push(ny);
        }
    }
}

int main()
{
    while(scanf("%d%d", &n, &m), n||m)
    {
        for(int i=1; i<=n; i++)
            for(int j=1; j<=m; j++)
                scanf(" %c", &mm[i][j]);
        memset(vis, 0, sizeof(vis));
        ans=0;
        for(int i=1; i<=n; i++)
        {
            for(int j=1; j<=m; j++)
            {
                if(mm[i][j]=='@'&&vis[i][j]==0)
                {
                    bfs(i, j);
                    ans++;
                }
            }
        }
        printf("%d\n", ans);
    }
    return 0;
}