紅與黑

#include <iostream>
#include <cstring>
using namespace std;
const int maxn = 25; 
int dr[]={0,0,1,-1};
int dc[]={1,-1,0,0};
char data[maxn][maxn]; 
int vis[maxn][maxn];
int dfs(int lr,int lc,int r,int c) {
        int ans = 0;
        vis[lr][lc]=1;
    for (int i=0;i<4;i++) {
        int nr = lr+dr[i];
        int nc = lc+dc[i];  
        if(nr>=1&&nr<=r&&nc>=1&&nc<=c) {
            if(vis[nr][nc]==0&&data[nr][nc]=='.')  {
                ans+=dfs(nr,nc,r,c);
                }
        }
    }

    return ans+1;
}


int main() {
    int r,c;
    cin>>r>>c;

    int lr,lc;
    for (int i=1;i<=r;i++)
     for (int j=1;j<=c;j++) {
        cin>>data[i][j];
         if(data[i][j]=='@') {
            lr = i; lc= j;
         }
     }

     memset(vis,0,sizeof(vis));
     vis[lr][lc]=1;
    int ans = dfs(lr,lc,r,c);
    cout<<ans<<endl;

}