백준 1012 유기농 배추(JAVA)

문제 설명

https://www.acmicpc.net/problem/1012

 

풀이과정

 DFS나 BFS로 풀이한다.

 

정답코드

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

public class Main {
    static int[] dy = {-1, 1, 0, 0};
    static int[] dx = {0, 0, -1, 1};
    static int[][] board;
    static boolean[][] visited;
    static int N, M, K;
    static int result = 0;

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

        int T = Integer.parseInt(br.readLine());
        StringTokenizer st;

        for (int i = 0; i < T; i++) {
            st = new StringTokenizer(br.readLine());
            M = Integer.parseInt(st.nextToken());
            N = Integer.parseInt(st.nextToken());
            K = Integer.parseInt(st.nextToken());

            board = new int[N][M];
            visited = new boolean[N][M];
            result = 0;

            for (int j = 0; j < K; j++) {
                st = new StringTokenizer(br.readLine());
                int x = Integer.parseInt(st.nextToken());
                int y = Integer.parseInt(st.nextToken());
                board[y][x] = 1;
            }

            for (int j = 0; j < N; j++) {
                for (int k = 0; k < M; k++) {
                    if (board[j][k] == 1 && !visited[j][k]) {
                        dfs(j, k);
                        result++;
                    }
                }
            }

            bw.write(result + "\n");
        }

        bw.flush();
    }

    public static void dfs(int y, int x) {

        if (visited[y][x]) {
            return;
        }

        visited[y][x] = true;

        for (int i = 0; i < 4; i++) {
            int ny = y + dy[i];
            int nx = x + dx[i];

            if (ny >= 0 && ny < N && nx >= 0 && nx < M) {
                if (board[ny][nx] == 1 && !visited[ny][nx]) {
                    dfs(ny, nx);
                }
            }
        }
    }
}