largest number formed from array.cpp

/*
///////////////////////////////////////////
//Question/Info

Largest Number formed from an Array
Medium Accuracy: 50.0% Submissions: 10534 Points: 4
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.

Example 1:

Input:
N = 5
Arr[] = {3, 30, 34, 5, 9}
Output: 9534330
Explanation: Given numbers are {3, 30, 34,
5, 9}, the arrangement 9534330 gives the
largest value.
Example 2:

Input:
N = 4
Arr[] = {54, 546, 548, 60}
Output: 6054854654
Explanation: Given numbers are {54, 546,
548, 60}, the arrangement 6054854654
gives the largest value.
Your Task:
You don't need to read input or print anything. Your task is to complete the function printLargest() which takes the array of strings arr[] as parameter and returns a string denoting the answer.

Expected Time Complexity: O(NlogN)
Expected Auxiliary Space: O(1)

Constraints:
1 ≤ N ≤ 105
0 ≤ Arr[i] ≤ 1018



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author: srj_v
///////////////////////////////////////////
*/

#include <bits/stdc++.h>
using namespace std;

// #define int 		   long long int
#define sbit(x) 	   __builtin_popcount(x)
#define pb(x) 		   push_back(x)
#define mp(x,y) 	   make_pair(x,y)
#define eb(x) 		   emplace_back(x)
#define ct(x) 		   cout << x << "\n";
#define ct2(x,y) 	   cout << x << " " << y << "\n";
#define tc(x) 		   cout << x << " ";
#define tc2(x,y) 	   cout << x << " " << y << " ";
#define forn(i,n) 	   for(int i = 0; i < (int)(n); ++i)
#define forx(i,x,n)    for(int i = x; i < (int)(n); ++i)
#define nfor(i,n)      for(int i = n-1; i >= 0; --i)
#define all(v) 		   v.begin(),v.end()
#define fsp(x,y)       fixed << setprecision(y) << x
#define PI 			   3.1415926535897932384626433832795
#define MOD 		   1000000007 // (1e9+7)
#define pii 		   pair<int,int>
#define pis 		   pair<int,string>
#define vi  		   vector<int>
#define vii 		   vector<pii>
#define mii 		   map<int,int>
#define p_q            priority_queue // priority_queue<int> (&) priority_queue< int,vi,greater<int> >
#define _IOS      	   ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

typedef long double ld;
typedef long long int lli;

#pragma GCC optimize("Ofast")

void c_p_c()
{
#ifndef ONLINE_JUDGE
	freopen("input.txt", "r", stdin);
	freopen("output.txt", "w", stdout);
#endif
}


int32_t main() {
///////////
	c_p_c();
///////////
	_IOS
//////////

	// code

	/*
	int t ; cin >> t; while(t--){}
	*/


	class Solution {
	public:
		// The main function that returns the arrangement with the largest value as
		// string.
		// The function accepts a vector of strings

		/*
			bool compare(string a, string b){

			    string A = a+b;
			    string B = b+a;

			    int i = 0 ;

			    while(A[i] and B[i]){

			        if(A[i]>B[i]){
			            return true;
			        }
			        else if(A[i]<B[i]){
			            return false;
			        }

			        i++;
			    }
			    return -1;

			}

			*/

		string printLargest(vector<string> &arr) {
			// code here

			// sort(arr.begin(),arr.end(), compare);

			sort(arr.begin(), arr.end(), [] (string a, string b)
			{
				return a + b > b + a;
			}
			    );

			string s = "";

			for (int i = 0 ; i < arr.size() ; i++) {
				s += arr[i];
			}


			return s;

		}
	};



// cerr << "time: " << clock() << " ms" << '\n';
	return 0;
}