POJ1164 The Castle DFS

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本文介绍了一个基于深度优先搜索算法的程序，该程序用于计算一个由模块组成的虚拟城堡中的房间数量及最大房间的面积。输入包括城堡各模块的描述，输出则为房间总数和最大房间所占模块的数量。

Description

     1   2   3   4   5   6   7  

   #############################

 1 #   |   #   |   #   |   |   #

   #####---#####---#---#####---#

 2 #   #   |   #   #   #   #   #

   #---#####---#####---#####---#

 3 #   |   |   #   #   #   #   #

   #---#########---#####---#---#

 4 #   #   |   |   |   |   #   #

   #############################

(Figure 1)



#  = Wall   

|  = No wall

-  = No wall

Figure 1 shows the map of a castle.Write a program that calculates
1. how many rooms the castle has
2. how big the largest room is
The castle is divided into m * n (m<=50, n<=50) square modules. Each such module can have between zero and four walls.

Input

Your program is to read from standard input. The first line contains the number of modules in the north-south direction and the number of modules in the east-west direction. In the following lines each module is described by a number (0 <= p <= 15). This number is the sum of: 1 (= wall to the west), 2 (= wall to the north), 4 (= wall to the east), 8 (= wall to the south). Inner walls are defined twice; a wall to the south in module 1,1 is also indicated as a wall to the north in module 2,1. The castle always has at least two rooms.

Output

Your program is to write to standard output: First the number of rooms, then the area of the largest room (counted in modules).

Sample Input

4
7
11 6 11 6 3 10 6
7 9 6 13 5 15 5
1 10 12 7 13 7 5
13 11 10 8 10 12 13

Sample Output

5
9

Source

IOI 1994

简单深度搜索题

#include <iostream>
#include <cstdio>
#include <map>
#include <queue>
#include <stack>
#include <cmath>
#include <algorithm>
#include <cstring>
#include <string>
using namespace std;
#define INF 0x3f3f3f3f
typedef long long LL;
int a[55][55];
bool v[55][55];
int num,room,maxroom;

void dfs(int i,int j)
{
    if(!v[i][j])
        return;
    v[i][j]=false;
    room++;
    if((a[i][j]&1)==0) dfs(i,j-1);
    if((a[i][j]&2)==0) dfs(i-1,j);
    if((a[i][j]&4)==0) dfs(i,j+1);
    if((a[i][j]&8)==0) dfs(i+1,j);
}
int main()
{
    int n,m;
    while(~scanf("%d%d",&n,&m)){
        for(int i=0;i<n;i++){
            for(int j=0;j<m;j++){
                scanf("%d",&a[i][j]);
            }
        }
        memset(v,true,sizeof(v));
        num=maxroom=0;
        for(int i=0;i<n;i++){
            for(int j=0;j<m;j++){
                if(v[i][j]){
                    num++;
                    room=0;
                    dfs(i,j);
                    maxroom=max(maxroom,room);
                }
            }
        }
        printf("%d\n%d\n",num,maxroom);
    }
    return 0;
}