[Java] 백준 / 집합의 표현 / 1717번

[Java] 백준 / 집합의 표현 / 1717번

문제

집합의 표현 문제 링크

접근 방식

유니온 파인드 구현 연습

코드

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main_1717 {

	static int[] parents;
	static int n,m;
	public static void main(String[] args) throws IOException{
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(br.readLine());
		
		n = Integer.parseInt(st.nextToken());
		m = Integer.parseInt(st.nextToken());
		
		makeSet(); 
		
		for(int i=0;i<m;i++) {
			st = new StringTokenizer(br.readLine());
			
			int command = Integer.parseInt(st.nextToken());
			int a = Integer.parseInt(st.nextToken());
			int b = Integer.parseInt(st.nextToken());
			
			if(command == 0) {
				union(a,b);
			}
			else {
				if(findSet(a) == findSet(b)) {
					System.out.println("YES");
				}
				else {
					System.out.println("NO");
				}
			}
		}
	}
	
	public static void makeSet() {
		parents = new int[n+1];
		
		for(int i=1;i<=n;i++) {
			parents[i] = i;
		}
	}
	
	public static int findSet(int a) {
		if(a == parents[a]) return a;
		return parents[a] = findSet(parents[a]);
	}
	
	public static boolean union(int a, int b) {
		if(findSet(a) == findSet(b)) return false;
		parents[findSet(b)] = findSet(a);
		return true;
	}

}