Red and Black&&http://acm.hdu.edu.cn/showproblem.php?pid=1312

DFS不解释。。

#include<iostream>#include<string.h>#include<string>#include<cstdio>#define N  50using namespace std;int n,m;char map[N][N];int sum;void dfs(int x,int y){if(map[x+1][y]=='.') {sum++;map[x+1][y]='#';dfs(x+1,y);}if(map[x-1][y]=='.') {sum++;map[x-1][y]='#';dfs(x-1,y);}if(map[x][y-1]=='.') {sum++;map[x][y-1]='#';dfs(x,y-1);}if(map[x][y+1]=='.') {sum++;map[x][y+1]='#';dfs(x,y+1);}}int main(){while(cin>>m>>n){if(!n&&!m) break;memset(map,'\0',sizeof(map));sum=1;int a,b;for(int i=0;i<n;++i){cin>>map[i];   for(int j=0;j<m;++j)if(map[i][j]=='@') a=i,b=j;    }map[a][b]='#';  dfs(a,b);  cout<<sum<<endl;}return 0;}