using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    static int[] GetSupplyIndexesBySupplyNumber(int[] actualPowerSupplyCounts, int supplyNumber)

    {

        var suppliesStartIndex = actualPowerSupplyCounts.Length * (supplyNumber - 1);

​

​

        var result = new List<int>();

        for (int i = 0; i < actualPowerSupplyCounts.Length; i++)

        {

            if (actualPowerSupplyCounts[i] >= supplyNumber)

            {

                result.Add(suppliesStartIndex + i);

            }

        }

        return result.ToArray();

    }

    public static void Main()

    {

        var actual        = new [] {0, 1, 2, 3, 4};

        var supplyNumbers = new [] {1, 2, 3, 4};

        foreach (var supplyNumber in supplyNumbers)

        {

            var indexes = GetSupplyIndexesBySupplyNumber(actual, supplyNumber);

            Console.WriteLine($"{supplyNumber} => {String.Join(",", indexes)}");

        }

    }

}