[Java] 백준 11724 연결된 요소의 개수

백준 11724 연결된 요소의 개수

문제 

- 문제 링크: 백준 11724 연결된 요소의 개수

풀이

import java.util.*;
import java.io.*;
 
class Main {
    static boolean[][] graph;
    static boolean[] visited;
    static int n,m;
    static int answer;
 
    static void dfs(int idx) {
       visited[idx] = true;
 
       for (int num =1; num <=n; num++) {
           if(!visited[num] && graph[idx][num])
               dfs(num);
       }
 
    }
 
    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());
 
        graph = new boolean[n+1][n+1];
        visited = new boolean[n+1];
        visited[0] = true;
 
        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][b] = true;
            graph[b][a] = true;
        }
        for(int j=0; j<n+1; j++) {
            if(visited[j]) {
                continue;
            }
            dfs(j);
            answer++;
        }
        bw.write(String.valueOf(answer));
 
        br.close();
        bw.close();
    }
}