Given an input array and target sum, find all possible ways the elements of the array can be added upto get target

sub_set_sum.rb

# Given an input array  and target sum, find all possible ways the elements of the array can be added upto get target
# sub_set_sum([10, 7, 5, 18, 12, 20, 15], 35) => [
#     [10, 7, 18],
#     [10, 5, 20]
#     [5, 18, 12],
#     [20, 15]
#   ]
require 'set'
def subset_sum(arr, sum, curr_arr = [], result = Set.new)
    return if arr.nil?
    if sum == 0
      unless result.include? curr_arr
        puts curr_arr.to_s
        result.add(curr_arr)
      end
    end
    return if arr.empty?
    num = arr[0]
    # not including the first element
    subset_sum(arr[1..-1], sum, Array.new(curr_arr), result)
    # including the first element
    subset_sum(arr[1..-1], sum - num, Array.new(curr_arr << num), result)
 end