백준 1743번 - 음식물 피하기

https://www.acmicpc.net/problem/1743

 

 

 

▶코드

import java.util.*;
import java.io.*;

public class Main {
    static int N, M, K;
    static int food[][];
    static boolean visited[][];
    static int dx[] = {0, 0, -1, 1};
    static int dy[] = {-1, 1, 0, 0};
    static int cnt;
    static LinkedList<Integer> result;

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st;
        st = new StringTokenizer(br.readLine());
        N = Integer.parseInt(st.nextToken());
        M = Integer.parseInt(st.nextToken());
        K = Integer.parseInt(st.nextToken());
        cnt = 1;
        if(K == 0)
            System.out.println(0);
        else{
            food = new int[N][M];
            visited = new boolean[N][M];
            result = new LinkedList<>();
            for (int i = 0; i < K; i++) {
                st = new StringTokenizer(br.readLine());
                int r = Integer.parseInt(st.nextToken());
                int c = Integer.parseInt(st.nextToken());
                food[r - 1][c - 1] = 1;
            }
            for(int i=0;i<N;i++){
                for(int j=0;j<M;j++){
                    if(!visited[i][j] && food[i][j] == 1){
                        dfs(i,j);
                        result.add(cnt);
                        cnt = 1;
                    }
                }
            }
            Collections.sort(result);
            System.out.println(result.get(result.size()-1));
        }
    }
    public static void dfs(int x, int y) {
        visited[x][y] = true;
        for (int i = 0; i < 4; i++) {
            int nx = dx[i] + x;
            int ny = dy[i] + y;
            if (nx >= 0 && ny >= 0 && nx < N && ny < M && !visited[nx][ny] && food[nx][ny] == 1){
                dfs(nx, ny);
                cnt++;
            }
        }
    }
}