/* 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
{
{
Scanner sc
= new Scanner
(System.
in); int t = sc.nextInt();
while(t-- > 0){
int n = sc.nextInt();
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
)); }
}
}
}
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