Oil Deposits

最新推荐文章于 2019-07-09 22:34:59 发布

原创最新推荐文章于 2019-07-09 22:34:59 发布 · 196 阅读

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本文介绍了一个用于探测地下油藏分布的算法实现，通过深度优先搜索（DFS）和广度优先搜索（BFS）两种方法来确定不同油藏的数量。算法在网格上运行，将每个含有石油的地块视为油藏的一部分，并通过相邻关系连接这些部分。

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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

代码dfs：

#include<cstdio>
#include<string.h>
#include<algorithm>
using namespace std;
const int MAX=1e2+10;
char s[MAX][MAX];
int n,m,vis[MAX][MAX];
int fxy[8][2]={{-1,0},{-1,1},{0,1},{1,1},{1,0},{1,-1},{0,-1},{-1,-1}}; // 8 个方向
int dfs(int x,int y)
{
vis[x][y]=1;//进过后设置成1保证不会在经过了
for(int i=0;i<8;i++)
{
int xx=x+fxy[i][0];
int yy=y+fxy[i][1];
if(xx >= 0 && yy >= 0 && xx < n && yy < m && !vis[xx][yy] && s[xx][yy] == '@') // 判断是否出界，是否已经搜索过，是否为油田
dfs(xx,yy);
}
}
int main()
{while(~scanf("%d%d",&n,&m)&&n+m)
{int ans=0;
memset(vis,0,sizeof(vis));
for(int i=0;i<n;i++)
scanf("%s",s[i]);
for(int i=0;i<n;i++)
for(int j=0;j<m;j++)
if(!vis[i][j]&&s[i][j]=='@')
ans++,dfs(i,j);
printf("%d\n",ans);
}
return 0;
}

代码bfs：

#include<cstdio>
#include<queue>
#include<cstring>
#include<algorithm>
using namespace std;
const int MAX = 1e2 + 10;
typedef long long LL;
char s[MAX][MAX];
int n,m,vis[MAX][MAX],ans;
int fx[8] = {0,0,-1,1,-1,1,-1,1},fy[8] = {-1,1,0,0,-1,-1,1,1};
struct node{
    int x,y;
};
void bfs(int x,int y){
    vis[x][y] = 1;
    queue <node> q;
    node o;
    o.x = x,o.y = y;
    q.push(o);
    while(!q.empty()){
        o = q.front();
        q.pop();
        for(int i = 0; i < 8; i++){ // 8 个方向  
            int xx = o.x + fx[i],yy = o.y + fy[i];
            if(xx >= 0 && yy >= 0 && xx < n && yy < m && !vis[xx][yy] && s[xx][yy] == '@'){  // 判断是否出界， 是否已经搜索过， 是否为油田 
                node w;
                vis[xx][yy] = 1;
                w.x = xx,w.y = yy;
                q.push(w);
            }
        }
    }
}
int main()
{
    while(~scanf("%d %d",&n,&m),m){
        memset(vis,0,sizeof(vis));
        for(int i = 0; i < n; i++)
            scanf("%s",s[i]);
        ans = 0;
        for(int i = 0; i < n; i++)
            for(int j = 0; j < m; j++)
                if(!vis[i][j] && s[i][j] == '@')
                    ans++,bfs(i,j); // // 第一次搜到 + 1  
        printf("%d\n",ans);
    }
    return 0;
}