[백준] 1260 DFS와 BFS - 자바

import java.io.*;
import java.util.LinkedList;
import java.util.Queue;
import java.util.StringTokenizer;

public class Main {
    static boolean[][] map;
    static boolean[] visited;
    static int N, M, V;
    static StringBuilder sb = new StringBuilder();
    static Queue<Integer> queue = new LinkedList<>();


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

        StringTokenizer st = new StringTokenizer(br.readLine());
        N = Integer.parseInt(st.nextToken());
        M = Integer.parseInt(st.nextToken());
        V = Integer.parseInt(st.nextToken());

        map = new boolean[N + 1][N + 1];
        visited = new boolean[N + 1];

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

            map[x][y] = true;
            map[y][x] = true;
        }

        dfs(V);
        sb.append("\n");

        visited = new boolean[N + 1];
        bfs(V);

        bw.write(sb + "\n");
        bw.flush();

        br.close();
        bw.close();
    }

	//재귀를 통해 하나씩 찾아나가는 방식
    public static void dfs(int idx){
        visited[idx] = true;
        sb.append(idx).append(" ");

        for(int i=1; i<=N; i++){
            if(!visited[i] && map[idx][i]){
                dfs(i);
            }
        }
    }

	/*현재 노드의 자식 노드를 전부 큐에 넣어서 
    큐의 노드를 하나씩 확인하는 방식*/
    public static void bfs(int idx){
        visited[idx] = true;
        queue.add(idx);

        while (!queue.isEmpty()){
            int index = queue.poll();
            sb.append(index).append(" ");

            for(int i=1; i<=N; i++){
                if(!visited[i] && map[index][i]){
                    visited[i] = true;
                    queue.add(i);
                }
            }
        }
    }
}