친구인가?

이 코드는 재귀를 사용하여 서로의 상관 관계를 확인하면서 서로 연관이 되어있다면 배열을 통해서 서로에게 연관이 가는 곳의 인댁스로 옮겨주는 코드이다.

import java.util.ArrayList;
import java.util.Arrays;
import java.util.PriorityQueue;
import java.util.Scanner;

public class Main {
    static int dis[];
    public static void Union(int a, int b) {
        int da = Find(a);
        int db = Find(b);
        if(da!=db) dis[da]=db;
    }

    private static int Find(int a) {
        if(dis[a]==a)return a;
        else return dis[a]=Find(dis[a]);
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int m = sc.nextInt();
        dis= new int[n + 1];
        System.out.println();
        for(int i=1;i<=n;i++)dis[i]=i;
        for (int i =1; i <=m; i++) {
            int a = sc.nextInt();
            int b = sc.nextInt();
            Union(a,b);
        }
        int x=sc.nextInt();
        int y= sc.nextInt();
        int Fa=Find(x);
        int Fb =Find(y);
        if(Fa==Fb) System.out.println("YES");
        else System.out.println("NO");
    }


}