[백준] 11724 : 연결 요소의 개수 - JAVA

문제

https://www.acmicpc.net/problem/11724

11724번: 연결 요소의 개수

 

코드

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

class Main {	
	
	public static void main(String args[]) throws Exception{
		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());
		
		ArrayList<Integer> graph [] = new ArrayList [n+1];
		for(int i=0;i<=n;i++) {
			graph[i] = new ArrayList<>();
		}
		
		for(int i=0;i<m;i++) {
			st = new StringTokenizer(br.readLine());
			int a = Integer.parseInt(st.nextToken());
			int b = Integer.parseInt(st.nextToken());
			graph[a].add(b);
			graph[b].add(a);
		}
		
		Queue<Integer> que = new LinkedList<>();
		boolean visited[] = new boolean [n+1];
		int count = 0;
		for(int i=1;i<=n;i++) {
			if(visited[i]) continue;
			count += 1;
			que.add(i);
			
			while(!que.isEmpty()) {
				int cur = que.poll();
				
				for(int next : graph[cur]) {
					if(visited[next]) continue;
					que.add(next);
					visited[next] = true;
				}
			}
		}
		
		System.out.print(count);
		
	}

}