Generate number of sub arrays with a particular sum: E.g. nums = [1,1,1] with sum 2
arr = [1,1,1] SUM =2 #arr = [1,2,2,3,4,5] #SUM = 5 sub_arrays = [] arr = arr.sort arr.each_with_index do |n, index| if n == SUM sub_arrays << [n] next end rest_of_array = arr[(index+1)..-1] temp_arr = [n] rest_of_array.each do |m| temp_arr << m if temp_arr.sum == SUM # We found a sub_array! sub_arrays << temp_arr # There might be duplicates of m, so let us remove m from temp_arr and continue temp_arr = temp_arr[0..temp_arr.length-2] end if temp_arr.sum < SUM # do nothing; we can continue to add more elements end if temp_arr.sum > SUM # discard all elements except n temp_arr = [n] end end end puts sub_arrays.to_s