2d array row sum

[White Crime]

I have 2d array 4x5. How can i find average value of each row, and then print out row numbers in decreasing order of their average values?

#include "pch.h"
#include <iostream>
using namespace std;

int main() {
	int i, j;
	int arr[4][5] = { 
		{11, 12, 13, 14, 16},
	    {21, 22, 55, 23, 24},
	    {31, 32, 33, 34, 65},
	    {13, 33, 44, 55, 55}
	};

	for (i = 0; i < 4; i++) {
		for (j = 0; j < 5; j++) {
			cout << arr[i][j] << " ";
		}
		cout << "\n";
	}
	
	return 0;
}

[lastchance]

#include <iostream>
#include <string>
#include <vector>
#include <valarray>
#include <algorithm>
using namespace std;


using ROW = valarray<int>;


void print( const string &title, const vector<ROW> &M )
{
   if ( title != "" ) cout << title << '\n';
   for ( auto &row : M )
   {
      for ( auto e : row ) cout << e << '\t';
      cout << "Average: " << (double)row.sum() / row.size() << '\n';
   }
}


int main()
{
   vector<ROW> M = { { 11, 12, 13, 14, 16 },
                     { 21, 22, 55, 23, 24 },
                     { 31, 32, 33, 34, 65 },
                     { 13, 33, 44, 55, 55 } };
   print( "Before:", M );

   // Sort for DECREASING average
   sort( M.begin(), M.end(), []( ROW a, ROW b ){ return a.sum() > b.sum(); } );
   print( "\nAfter:", M );
}

Before:
11	12	13	14	16	Average: 13.2
21	22	55	23	24	Average: 29
31	32	33	34	65	Average: 39
13	33	44	55	55	Average: 40

After:
13	33	44	55	55	Average: 40
31	32	33	34	65	Average: 39
21	22	55	23	24	Average: 29
11	12	13	14	16	Average: 13.2

[White Crime]

Thanks for solving it, but its just too complicated for me, im just begginner, is there any easier way with some basic skills?

[Grunalin]

White cream, as a beginner it worth looking over the code and work out what it doing..... best way to learn (as I am currently)

In last chances code ignore the print function, that just for nice display output, it nothing that solves the problem.

A Vector is similar to your use of int array (int arr[4][5]) call but a vector offers other functionality such as sort.

In the line
sort( M.begin(), M.end(), []( ROW a, ROW b ){ return a.sum() > b.sum(); } );
he sorts the vector by highest sum in each, if you only have 5 elements in each row sorting by average is same as total value. This the line that sorts the data to how you want.

As a beginner I would advise to look at vectors, you will come across them a lot.

As for the average, for display purposes it is in the print function on the cout statement
cout << "Average: " << (double)row.sum() / row.size() << '\n';
but it is not kept/recorded anywhere.
row.sum taking total of values, row.size number of elements.

Hope that helps a little.

Grun
PS still noob myself so hope you get better answer