AcWing 1113. 红与黑（dfs）

Problem

dfs，这个题没有要求一个最值，可以用dfs，模板题

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;

class Main {
    static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    static PrintWriter pw = new PrintWriter(System.out);
    static int N = 25, n, m;
    static boolean st[][];
    static char g[][] = new char[N][N];
    static int dx[] = new int[]{1, 0, -1, 0};
    static int dy[] = new int[]{0, -1, 0, 1};

    public static void main(String[] args) throws Exception {
        while (true) {
            String s[] = br.readLine().split(" ");
            if (s[0].equals("0") || s[1].equals("0")) break;
            st = new boolean[N][N];
            m = Integer.parseInt(s[0]);
            n = Integer.parseInt(s[1]);
            int x = 0, y = 0;
            for (int i = 0; i < n; i++) {
                String ss = br.readLine();
                for (int j = 0; j < m; j++) {
                    g[i][j] = ss.charAt(j);
                    if (g[i][j] == '@') {
                        x = i;
                        y = j;
                    }
                }
            }

            pw.println(dfs(x, y));

        }
        pw.flush();
        pw.close();
        br.close();
    }

    public static int dfs(int x, int y) {
        int cnt = 1;
        st[x][y] = true;
        for (int i = 0; i < 4; i++) {
            int px = x + dx[i];
            int py = y + dy[i];
            if (px < 0 || px >= n || py < 0 || py >= m) continue;
            if (g[px][py] == '@') continue;
            if (g[px][py] == '#') continue;
            if (st[px][py]) continue;
            cnt += dfs(px, py);
        }
        return cnt;
    }
}