BFS广度优先搜索(5)(亦可以用DFS)--hdu1241(poj1562)(基础题)

来源：互联网发布：清华大学王斌算法考试编辑：程序博客网时间：2024/06/04 18:27

Oil Deposits

Time Limit:1000MS Memory Limit:32768KB 64bit IO Format:%I64d & %I64u

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

这道题就是给你一个二维数组，‘@’周围八个方向的‘@’都是属于同一块区域，问这个二维数组被分为几个区域。简单的BFS，直接向八个方向搜索，BFS与DFS两种方法我都写了，BFS代码：

#include<stdio.h>#include<string.h>#include<queue>using namespace std;char map[105][105];int vis[105][105];int n,m;int d[8][2]={{0,1},{0,-1},{1,0},{-1,0},            {1,1},{-1,-1},{-1,1},{1,-1}};       //八个方向struct node{int x;int y;};void Bfs(int x,int y){vis[x][y]=1;queue<node>q;node s,e;int i;s.x=x;s.y=y;q.push(s);while(!q.empty()){s=q.front();q.pop();for(i=0;i<8;i++){int xx=s.x+d[i][0];int yy=s.y+d[i][1];if(xx<0||yy<0||xx>=n||yy>=m)continue;if(map[xx][yy]=='*')continue;if(vis[xx][yy])continue;vis[xx][yy]=1;e.x=xx;e.y=yy;q.push(e);}}}int main(){int i,j;int ans;while(scanf("%d %d",&n,&m)!=EOF){if(!n&&!m)break;memset(vis,0,sizeof(vis));ans=0;for(i=0;i<n;i++){scanf("%s",map[i]);}for(i=0;i<n;i++){for(j=0;j<m;j++){if(map[i][j]=='@'&&!vis[i][j]){Bfs(i,j);ans++;}}}printf("%d\n",ans);}return 0;}

DFS代码:

#include<stdio.h>#include<string.h>int n,m;char map[105][105];int vis[105][105];int d[8][2]={{0,1},{0,-1},{1,0},{-1,0},            {1,1},{-1,-1},{-1,1},{1,-1}};  //八个方向void Dfs(int x,int y){int i;for(i=0;i<8;i++){int xx=x+d[i][0];int yy=y+d[i][1];if(xx<0||yy<0||xx>=n||yy>=m)continue;if(map[xx][yy]=='*')continue;if(vis[xx][yy])continue;vis[xx][yy]=1;Dfs(xx,yy);}}int main(){int i,j;int ans;while(scanf("%d %d",&n,&m)!=EOF){if(!n&&!m)break;ans=0;memset(vis,0,sizeof(vis));for(i=0;i<n;i++){scanf("%s",map[i]);}for(i=0;i<n;i++){for(j=0;j<m;j++){if(map[i][j]=='@'&&!vis[i][j]){Dfs(i,j);ans++;}}}printf("%d\n",ans);}return 0;}

两种方法：第一个是DFS

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