로봇 청소기

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.Queue;
import java.util.Scanner;

public class Main {
	static class Node {
		int r;
		int c;

		Node(int r, int c) {
			this.r = r;
			this.c = c;
		}
	}

	static int[][] arr;
	static int R;
	static int C;

	static int[] dr = { -1, 1, 0, 0 };
	static int[] dc = { 0, 0, -1, 1 };

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);

		R = sc.nextInt();
		C = sc.nextInt();

		arr = new int[R][C];

		ArrayList<Node> list = new ArrayList<>();

		for (int i = 0; i < R; i++) {
			for (int j = 0; j < C; j++) {
				arr[i][j] = sc.nextInt();
				if (arr[i][j] == 0) {
					list.add(new Node(i, j));
				}
			}
		}

		c(list, 0, 0, new Node[3]);

		System.out.println(max);
		max = 0;

	}

	static int max = 0;

	static void c(ArrayList<Node> list, int n, int c, Node[] re) {
		if (c == re.length) {

			int[][] tmp = new int[R][C];
			for (int i = 0; i < R; i++) {
				for (int j = 0; j < C; j++) {
					tmp[i][j] = arr[i][j];
				}
			}

			for (int i = 0; i < 3; i++) {
				//System.out.print(re[i].r + " " + re[i].c + "     ");
				tmp[re[i].r][re[i].c] = 1;
			}
			//System.out.println();

			Queue<Node> q = new LinkedList<>();
			boolean[][] che = new boolean[R][C];

			for (int i = 0; i < R; i++) {
				for (int j = 0; j < C; j++) {
					if (tmp[i][j] == 2) {
						q.add(new Node(i, j));
						che[i][j] = true;
						while (!q.isEmpty()) {
							Node node = q.poll();
							for (int k = 0; k < 4; k++) {
								int nr = node.r + dr[k];
								int nc = node.c + dc[k];
								if (nr >= 0 && nc >= 0 && nr < R && nc < C && tmp[nr][nc] == 0
										&& che[nr][nc] == false) {
									tmp[nr][nc] = 2;
									q.add(new Node(nr, nc));
									che[nr][nc] = true;
								}
							}
						}
					}
				}
			}
			int cnt = 0;

			for (int i = 0; i < R; i++) {
				for (int j = 0; j < C; j++) {
					//System.out.print(tmp[i][j] + " ");
					if (tmp[i][j] == 0) {
						cnt++;
					}
				}
				//System.out.println();
			}

			if (max < cnt)
				max = cnt;

			//System.out.println();
			return;
		}
		if (n == list.size()) {
			return;
		}
		re[c] = list.get(n);
		c(list, n + 1, c + 1, re);
		c(list, n + 1, c, re);
	}
}