Iterative Ruby solution to "Problem 5"

problem5.rb

def get_operands(comma_indexes)
  base = (1..9).to_a
  last_index = 0
  operands = []
  comma_indexes.each do |comma_index|
    operands.push(base[last_index..(comma_index-1)].join)
    last_index = comma_index
  end
  operands.push(base[last_index..8].join)
  get_plus_minus_combinations_100(operands)
end

def get_plus_minus_combinations_100(operands)
  # create a clean copy
  operands_copy = operands.clone
  # get the number of operators
  num_operators = operands.length - 1
  # available operators
  operations = ['+','-']

  operations.repeated_permutation(num_operators).each_with_index do |operation_order|
    count = 1
    operation_order.each do |operation|
      operands.insert(count, operation)
      count = count + 2
    end
    count = 0
    if eval(operands.join) == 100
      puts operands.join(' ')
    end

    operands = operands_copy.clone
  end
end

# We are going to do varied sizes of combinations of indexes to indicate where
# the splits should be for each number of commas
indexes = [1,2,3,4,5,6,7,8]

# Find the combinations of indexes for one comma, then two commas...
(1..8).each do |i|
  indexes.combination(i).each do |comb|
    get_operands(comb)
  end
end