Order Prosperity - JAVA

import java.util.*;

class Pair{
    int ff;
    int ss;
    public Pair(int f,int s) {
        ff = f;
        ss = s;
    }
}

class CustomSort implements Comparator<Pair>{

    @Override
    public int compare(Pair a, Pair b) {
        if(a.ss!=b.ss) {
            return b.ss-a.ss;
        }
        return b.ff-a.ff;
    }

}


public class Solution {

    static Scanner sc = new Scanner(System.in);

    public static void dfsUtil(ArrayList<Integer>[] A,int src,int par,int[] citiesCanBeVisited) {
        int ans = 0;

        for(int i : A[src]) {
            if(i!=par) {
                dfsUtil(A,i,src,citiesCanBeVisited);
                ans+=(citiesCanBeVisited[i]+1);
            }
        }
        citiesCanBeVisited[src] = ans;
    }

    public static ArrayList<Integer> orderProsperity(int N, ArrayList<Integer>[] A){
        ArrayList<Integer> result = new ArrayList<>();

        int[] citiesVisited = new int[N+1];
        for(int i=0;i<=N;i++) {
            citiesVisited[i] = -1;
        }

        Queue<Integer> q = new LinkedList<>();
        q.add(1);
        citiesVisited[1] = 0;

        while(!q.isEmpty()) {
            int temp = q.remove();
            for(int i : A[temp]) {
                if(citiesVisited[i] == -1) {
                    citiesVisited[i] = citiesVisited[temp]+1;
                    q.add(i);
                }
            }
        }

        int[] citiesCanBeVisited = new int[N+1];
        for(int i=0;i<=N;i++) {
            citiesCanBeVisited[i] = 0;
        }

        dfsUtil(A,1,-1,citiesCanBeVisited);

        ArrayList<Pair> dummy = new ArrayList<>();

        for(int i=1;i<=N;i++) {
            dummy.add(new Pair(i,citiesCanBeVisited[i] * citiesVisited[i]));
        }

        Collections.sort(dummy, new CustomSort());


        for(Pair i : dummy) {
            result.add(i.ff);
        }

        return result;
    }

    public static void main(String[] args) {
        int N;
        N = sc.nextInt();

        ArrayList<Integer>[] A = new ArrayList[N+1];

        for(int i=0;i<=N;i++) A[i] = new ArrayList<>();

        for(int i=0;i<N-1;i++) {
            int temp1 = sc.nextInt();
            int temp2 = sc.nextInt();

            A[temp1].add(temp2);
            A[temp2].add(temp1);
        }

        ArrayList<Integer> result= orderProsperity(N,A);

        for(int i : result) {
            System.out.print(i + " ");
        }

        System.out.println();
    }
}