/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Solution
{
	public static void main (String[] args) throws java.lang.Exception
	{
		Scanner sc = new Scanner(System.in);
		int t = sc.nextInt();
 
		while(t-- > 0){
			int n = sc.nextInt();
			String[] arr = new String[n];
 
			for(int i = 0; i < n; i++){
				arr[i] = String.valueOf(sc.nextInt());
			}
 
			ArrayList<String> solutionList = new ArrayList<>(Arrays.asList(arr)); 
 
			Collections.sort(solutionList, (x, y) -> (y + x).compareTo(x + y));
 
			for(int i = 0; i < n; i++){
				System.out.print(solutionList.get(i));
			}
 
			System.out.println();
		}
	}
}

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Mwo4CjQ5IDczIDU4IDMwIDcyIDQ0IDc4IDIzIAo0CjY5IDkgNTcgNjAgCjIKNDAgNCA=

3
8
49 73 58 30 72 44 78 23 
4
69 9 57 60 
2
40 4