Rearrange Array Numbers to form Largest Possible Number

#include <bits/stdc++.h>
#include <string>
bool compare(int a , int b)
{
    string s1 = to_string(a) ; 
    string s2 = to_string(b) ;

    return s1 + s2 > s2 + s1 ; 
    
        


}




string formLargestPossibleNumber(int arr[], int n) 
{
    // Write your code here.
    sort(arr , arr + n , compare) ;
    string res="" ;
    for(int i = 0  ; i < n ; i++)
    {
        res = res + to_string(arr[i]) ;
    }
    return res ;
    
}