백준 5567 결혼식(Java)

https://www.acmicpc.net/problem/5567

5567번: 결혼식

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Java 코드

 

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import java.util.Scanner;
import java.util.ArrayList;

public class Main {

  static int count = 0;
  static int n;
  static int m;
  static ArrayList<ArrayList<Integer>> list;
  static boolean[] visit;
  
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);

    n = sc.nextInt();
    m = sc.nextInt();
    list = new ArrayList<>();
    visit = new boolean[n + 1];

    for(int i = 0; i <= n; i++) list.add(new ArrayList<>());

    for(int i = 0; i < m; i++) {
      int a = sc.nextInt();
      int b = sc.nextInt();
      list.get(a).add(b);
      list.get(b).add(a);
    }

    dfs(0, 1);

    for(int i = 2; i <= n; i++) {
      if(visit[i] == true) count++;
    }
      
    System.out.println(count);
  }

  public static void dfs(int dep, int start) {
    if(dep == 2) return;
    
    for(int i : list.get(start)) {
        visit[i] = true;
        dfs(dep + 1, i);
    }
    
  }
}