Time Range

time-range.rb

require 'time'
require 'pp'

objects = [Time.strptime("20", "%M"), Time.strptime("21", "%M"), Time.strptime("25", "%M"),Time.strptime("26", "%M")]
@range  = Hash.new { |hash, key| hash[key] = [] }

def add_into_time_range(time)
  base = time.min - (time.min % 5)
  key  = "#{time.hour}:#{base}"
  
  @range[key] << time
end

objects.each { |t| add_into_time_range(t) }

pp @range

# {
# "14:20"=>[2018-01-12 14:20:00 +0100, 2018-01-12 14:21:00 +0100],
# "14:25"=>[2018-01-12 14:25:00 +0100, 2018-01-12 14:26:00 +0100]
# }