백준 21736

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.LinkedList;
import java.util.Queue;
import java.util.StringTokenizer;

public class Main21736 {
	
	static int[] dx = {-1,1,0,0}; //상하좌우 
	static int[] dy = {0,0,-1,1}; 
	static char[][] map;
	static boolean[][] visit;
	static int M,N;

	public static void main(String[] args) throws IOException {
		
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(br.readLine());
		N = Integer.parseInt(st.nextToken());
		M = Integer.parseInt(st.nextToken());
		map = new char[N][M];
		visit = new boolean[N][M];
		
		int x = 0, y = 0;
		
		for(int i=0; i<N; i++) {
			String str = br.readLine();
			for(int j=0; j<M; j++) {
				
				map[i][j] = str.charAt(j);
				if(map[i][j] == 'I') {
					x = i;
					y = j;			
				}
			}		
		}

		int cnt = 0;
		
		Queue<Pair> q = new LinkedList<>();
		q.add(new Pair(x,y));
		visit[x][y] = true;
		
		while(!q.isEmpty()) {
			Pair pair = q.peek();
			int cx = pair.x;
			int cy = pair.y;
			q.poll();
			
			if(map[cx][cy] == 'P') {
				cnt++;
			}

			for(int i=0; i<4; i++) {
				int nx = cx+dx[i];
				int ny = cy+dy[i];
				
				if (valid(nx, ny)) {
					visit[nx][ny] = true;
					q.add(new Pair(nx,ny));	
				}		
			}
				
		}
		
		if(cnt == 0) {
			System.out.println("TT");
		}
		else {
			System.out.println(cnt);
		}
	}
	
	static boolean valid(int x, int y) {
		if(x<0 || x>N-1 || y<0 || y >M-1 || map[x][y] == 'X' || visit[x][y]) {
			return false;
		}
		return true;
	}
	
	static class Pair{
		int x;
		int y;

		public Pair(int x, int y) {
			this.x = x;
			this.y = y;
		}
		
	}
}

dfs사용

package Cho.week_5;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main21736_1 {
	
	static int[] dx = {-1,1,0,0}; //상하좌우 
	static int[] dy = {0,0,-1,1}; 
	static char[][] map;
	static boolean[][] visit;
	static int M,N;

	public static void main(String[] args) throws IOException {
		
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(br.readLine());
		N = Integer.parseInt(st.nextToken());
		M = Integer.parseInt(st.nextToken());
		map = new char[N][M];
		visit = new boolean[N][M];
		
		int x = 0, y = 0;
		
		for(int i=0; i<N; i++) {
			String str = br.readLine();
			for(int j=0; j<M; j++) {
				
				map[i][j] = str.charAt(j);
				if(map[i][j] == 'I') {
					x = i;
					y = j;			
				}
			}		
		}

		int cnt = dfs(new Pair(x,y), 0);

		if(cnt == 0) {
			System.out.println("TT");
		}
		else {
			System.out.println(cnt);
		}
	}
	
	static int dfs(Pair pair, int cnt) {
		int cx = pair.x;
		int cy = pair.y;
		
		if(map[cx][cy] == 'P') {
			cnt++;
		}
		
		for(int i=0; i<4; i++) {
			int nx = cx+dx[i];
			int ny = cy+dy[i];
			if(valid(nx,ny)) {
				visit[nx][ny] = true;
				cnt = dfs(new Pair(nx,ny), cnt);
			}
			
		}
		
		return cnt;
	}
	
	static boolean valid(int x, int y) {
		if(x<0 || x>N-1 || y<0 || y >M-1 || map[x][y] == 'X' || visit[x][y]) {
			return false;
		}
		return true;
	}
	
	static class Pair{
		int x;
		int y;

		public Pair(int x, int y) {
			this.x = x;
			this.y = y;
		}
		
	}
}