[JAVA/백준] 삼성 SW 역량 테스트 기출 문제: 연구소

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import java.util.ArrayList;
import java.util.Scanner;

/**
 * @author HEESOO
 *
 */
class Node{
	int x;
	int y;
	public Node(int x, int y) {
		this.x=x;
		this.y=y;
	}
}
public class Main {
	static int m, n, answer=0;
	static int[][] map, temp;
	static ArrayList<Node> virus;
	public static void comb(int start, int depth) {
		if(depth==3) {
			copyMap();
			for(int i=0;i<virus.size();i++) {
				Node node=virus.get(i);
				dfs(node.x, node.y);
			}
			zeroCount();
			return;
		}
		else {
			for(int i=start;i<n*m;i++) {
				int x=i/m;
				int y=i%m;
				if(map[x][y]==0) {
					map[x][y]=1;
					comb(i+1, depth+1);
					map[x][y]=0;
				}
			}
		}
	}
	public static void copyMap() {
		temp=new int[n][m];
		for(int i=0;i<n;i++) {
			for(int j=0;j<m;j++) {
				temp[i][j]=map[i][j];
			}
		}
	}
	public static void dfs(int x, int y) {
		int[] dotX= {0,0,-1,1};
		int[] dotY= {1,-1,0,0};
		for(int i=0;i<4;i++) {
			int xx=x+dotX[i];
			int yy=y+dotY[i];
			if(0<=xx&&xx<n&&0<=yy&&yy<m) {
				if(temp[xx][yy]==0) {
					temp[xx][yy]=2;
					dfs(xx,yy);
				}
			}
		}
	}
	public static void zeroCount() {
		int zero=0;
		for(int i=0;i<n;i++) {
			for(int j=0;j<m;j++) {
				if(temp[i][j]==0) zero++;
			}
		}
		answer=Math.max(answer, zero);
	}
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scan = new Scanner(System.in);
		n=scan.nextInt();
		m=scan.nextInt();
		map=new int[n][m];
		virus=new ArrayList<>();
		for(int i=0;i<n;i++) {
			for(int j=0;j<m;j++) {
				map[i][j]=scan.nextInt();
				if(map[i][j]==2) virus.add(new Node(i, j));
			}			
		}
		
		comb(0,0);
		System.out.println(answer);
	}
}