[規格]1260番DFSとBFS

問題I/O

質問へのアクセス

インプリメンテーションコード

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

public class Main {
  static ArrayList<Integer>[] al;
  static boolean check[];

  static void bfs(int a) {
    Queue<Integer> queue = new LinkedList<Integer>();
    queue.add(a);
    check[a] = true;

    while(!queue.isEmpty()) {
      int x = queue.poll();
      System.out.print(x + " ");
      for(int y : al[x]) {
        if(!check[y]) {
          check[y] = true;
          queue.add(y);
        }
      }
    }
  }

  static void dfs(int a) {
    if(check[a]) return;

    check[a] = true;
    System.out.print(a + " ");
    for(int y : al[a])
      if(!check[y])
        dfs(y);
  }

  public static void main(String[] args) throws IOException {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer(br.readLine());
    int N = Integer.parseInt(st.nextToken());
    int M = Integer.parseInt(st.nextToken());
    int V = Integer.parseInt(st.nextToken());

    al = new ArrayList[N+1];
    for(int i = 0; i < N + 1; i++) al[i] = new ArrayList<Integer>();

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

      al[a].add(b);
      al[b].add(a);
    }

    for (int i = 1; i < N + 1; i++) {
      Collections.sort(al[i]);
    }

    check = new boolean[N + 1];
    dfs(V);
    System.out.println();

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