1113. 红与黑 （ dfs / bfs ）

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import java.util.*;
import static java.lang.System.out;

public class Main{
    
    static int ans = 0;
    
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        
        while(true) {
            int r = in.nextInt();
            int c = in.nextInt();
            if(r == 0 && c == 0) break;
            char[][] cs = new char[c][r];
            
            for(int i = 0; i < c; i++) {
                String tmp = in.next();
                //out.println(tmp);
                cs[i] = tmp.toCharArray();
            }
            
            for(int i = 0; i < c; i++) {
                for(int j = 0; j < r; j++) {
                    if(cs[i][j] == '@') {
                        //起点
                        dfs(cs, i, j);
                        break;
                    }
                }
            }
            
            out.println(ans);
            ans = 0;
        }
        
    }
    
    public static void dfs(char[][] cs, int i, int j){
        
        ans++;
        cs[i][j] = '1';
        
        // 上下左右
        if(i + 1 < cs.length && cs[i + 1][j] == '.')
            dfs(cs, i + 1, j);
        if(i - 1 >= 0 && cs[i - 1][j] == '.')
            dfs(cs, i -1, j);
        if(j + 1 < cs[0].length && cs[i][j + 1] == '.')
            dfs(cs, i, j + 1);
        if(j - 1 >= 0 && cs[i][j - 1] == '.')
            dfs(cs, i, j - 1);
        
    }
    
}