Largest Number formed from an Array [HARD/IMP]

Company: Paytm, Amazon, MakeMyTrip

Given a list of non negative integers, arrange them in such a manner that they form the largest number possible.

The result is going to be very large, hence return the result in the form of a string.

Input:

The first line of input consists number of the test cases. The description of T test cases is as follows:

The first line of each test case contains the size of the array, and the second line has the elements of the array.

Output:

In each separate line print the largest number formed by arranging the elements of the array in the form of a string.

Constraints:

1 ≤ T ≤ 70
1 ≤ N ≤ 100
0 ≤ A[i] ≤ 1000

Example:

Input:

2
5
3 30 34 5 9
4
54 546 548 60

Output:

9534330
6054854654

CODE:

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

class Solution{
public static void main (String[] args) {
Scanner sc = new Scanner (System.in);
 int m=sc.nextInt();
 for(int mi=0;mi<m;mi++){
     int n=sc.nextInt();
     Vector <String> ar= new Vector<>();
        for(int i=0;i<n;i++){
         ar.add(Integer.toString(sc.nextInt()));
     }
     Collections.sort(ar,new Comparator<String>(){
        public int compare(String X, String Y) {
        String XY=X + Y;
        String YX=Y + X;
        return XY.compareTo(YX) > 0 ? -1:1;
    }
     });
     Iterator it = ar.iterator();

    while(it.hasNext())
        {System.out.print(it.next());}
        System.out.println();
     }
}

}

EXECUTION TIME: 0.21s