Largest Number formed from an Array

PROBLEM :
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

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SIMPLE c++ IMPLEMENTATION :
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#include<iostream>
using namespace std;
#include<algorithm>
#include<string.h>
#include <stdlib.h>
#define max 100

string Largest_Number(int [],int ) ;
int compare(int ,int ) ;
int append(int ,int ) ;

int main()
{
    int arr[max] ;
    int i,t,no ;
    cin>>t ;
    while(t--)
    {
        cin>>no ;
        for(i=0;i<no;i++)
            cin>>arr[i] ;
        cout<<Largest_Number(arr,no)<<endl ;
    }
 return 0;
}

string Largest_Number(int arr[],int no)
{
    int i ;
    string str="" ;
    sort(arr,arr+no,compare) ;

    for(i=0;i<no;i++)
        str=str+to_string(arr[i]) ;
     
    return str ;
}

int compare(int a,int b)
{
    return append(a,b)>append(b,a) ;
}

int append(int a,int b)
{
    int temp[10] ;
    int i,r ;
    i=0 ;
    while(b)
    {
        r=b%10 ;
        temp[i++]=r ;
        b=b/10 ;
    }
 
    for(r=i-1;r>=0;r--)
        a=a*10+temp[r] ;
     
    if(i==0)
        a=a*10 ;
     
    return a ;
}

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SIMPLE c++ IMPLEMENTATION : (better solution)
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#include<bits/stdc++.h>
using namespace std;

int compare(string s1,string s2)
{
    return s1+s2>s2+s1 ;
}
int main()
{
int t ;
cin>>t ;
while(t--)
{
   int no ;
   cin>>no ;
   vector<string> str ;
 
   int n ;
   for(int i=0;i<no;i++)
   {
       cin>>n ;
       str.push_back(to_string(n)) ;
   }
 
   sort(str.begin(),str.end(),compare) ;
 
   for(int i=0;i<no;i++)
       cout<<str[i] ;
     
   cout<<endl ;
 
}
return 0;
}

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