A smart-set is a set of distinct numbers in which all the elements have the same number of 1s in their binary form. The set of all smallest elements from each smart-set that can be formed from a given array of distinct positive numbers is known as the smartest-set.

smartest_set.rb

### smart sets, nestaway challenge skilenza
# Pseudo code
# Take number of test case
# Take array size
# Take array elements
# Test all are within give range
# Convert array elements into binary format
# Group binary elements based on number of 1's present
# Sort grouped elements in ascending order
# take first element from each set and display

test_cases_range = 1..1000 # ranges for input validation
arr_size_range = 1..10_000
arr_num_size_range = 1..100_000

test_cases = gets.chomp.to_i
if test_cases_range.cover? test_cases
  while test_cases > 0
    arr_size = gets.chomp.to_i
    if arr_size_range.cover? arr_size
      nums = gets.chomp
      nums = nums.split(' ').map(&:to_i) # input to integer arary
      if !nums.any? { |num| arr_num_size_range.cover? num }
        puts 'Array elements are out of range'
      else
        bin_hash = {}
        nums.each do |num|
          bin_hash[num.to_s] = num.to_s(2).scan(/1/).count # convert anc scan for 1's and store it in hash
        end
        bin_array = bin_hash.group_by { |_k, v| v }.sort.map(&:flatten) # group hash by comman values and sort. convert them to array groups
        bin_array = bin_array.map { |arr| arr.select { |n_arr| n_arr.class == String } } # extract input number from array group
        bin_array.each { |arr| arr.map!(&:to_i) } # convert array group to integers (easy for sorting)
        bin_array.each(&:sort!) # sort internal array elements
        res = bin_array.collect(&:first) # collect all first elements from array group
        res.each { |num| print num; print ' ' } # use print inorde tp print output in a line
        test_cases -= 1
        print "\n" # to print next set in next line
      end
    else
      puts 'array size number is out of range'
      end
  end
else
  puts 'test case numbers are out of range'
end