According to duration, split spots into different days

day-spliting.rb

# ActiveSupport has it.
class Array
  def sum
    if self.size == 0
      return 0
    else
      self.inject(:+)
    end
  end
end

## Demo for Spliting Days #################################

TOTAL_HOURS_A_DAY = 8
DURATIONS = [1,2,3,1,1,2,3,4,1,2,3,1,2,3,1,5,1,2,1,0.5,1,2]
splited_days = [[]]

DURATIONS.each do |duration, index|
  # has to be within TOTAL_HOURS_A_DAY
  # expected_trip_time = splited_days.last.sum + duration

  # A little more is fine
  expected_trip_time = splited_days.last.sum

  if expected_trip_time >= TOTAL_HOURS_A_DAY
    splited_days.push [duration]
  else
    splited_days.last.push duration
  end
end

# Show the result
splited_days.each do |a|
  puts a.inspect
  puts a.sum
end