permutation_sums.rb

def some_combination_of_the_numbers_adds_to_the_biggest_number(arr)
  arr = arr.sort
  biggest = arr.pop
  
  (2..arr.size).each do |perm_size|
    arr.permutation(perm_size).each do |nums|
      sum = nums.reduce(:+)
      return true if sum == biggest
    end
  end
  
  false
end

p some_combination_of_the_numbers_adds_to_the_biggest_number([1,2,3,4,8])