A little challenge @qmacro gave me, about time.

time_coincidences.rb

SECOND = 1
MINUTE = 60 * SECOND
HOUR = 60 * MINUTE

time = Time.new 0, 1, 1, 0, 0
end_time = Time.new 0, 1, 2, 0, 0

$coincidences = []

class Time
  def to_s
    hours = self.hour
    minutes = self.min
    time_string = "%02d:%02d" % [hours, minutes]
    return time_string
  end

  # Methods to check coincidences
  def palindrome?
    is_palindrome = self.to_s == self.to_s.reverse

    $coincidences.push self if is_palindrome

    return is_palindrome
  end

  def hours_are_same_as_mins?
    hours = "%02d" % [self.hour]
    mins = "%02d" % [self.min]

    hours_are_same_as_mins = hours == mins

    $coincidences.push self if hours_are_same_as_mins

    return hours_are_same_as_mins
  end

  def ladder?
    hours = "%02d" % [self.hour]
    mins = "%02d" % [self.min]

    first_digit = hours[0].to_i

    ladder_asc = [first_digit, first_digit+1, first_digit+2, first_digit+3].map {|e| e.to_s}

    time_arr = (hours + mins).split ""

    ladder = time_arr == ladder_asc

    $coincidences.push self if ladder

    return ladder
  end

end

while time < end_time
  time += MINUTE
  next if time.palindrome?
  next if time.hours_are_same_as_mins?
  next if time.ladder?

end

puts $coincidences