Saari Development

While discussing my friend Arsalan’s C# (seemlessly compiled on my linux machine using mcs)
solution and testing it out I found a bug in my own code that. The problem was when adding
more than 12 hours (> 720 minutes) it was not doing the right thing. The code can still be
refactored for cleaner solution but it is too late at night to do that now. Also, my wife
gave me another idea to convert the time to minutes before adding which I will try out later.

   # Without using any built in date or time functions, write a function or method
   # that accepts two mandatory arguments. The first argument is a string of the
   # format "[H]H:MM {AM|PM}" and the second argument is an integer. Assume the
   # integer is the number of minutes to add to the string. The return value of
   # the function should be a string of the same format as the first argument.
   # For example AddMinutes(" AM",) would return " AM". The exercise
   # isn't meant to be too hard. I just want to see how you code. Feel free to
   # do it procedurally or in an object oriented way, whichever you prefer. Use
   # any language you want. Write production quality code.
  # Question Source: http://blist.com/blog/

  # the following solution was developed using TDD

  require 'test/unit'

  class TestTimeCalc < Test::Unit::TestCase

      def setup
          @time = " AM"
      end

      def test_new_time_cal
          assert_not_nil(TimeCalc.new)
      end

      def test_add_minute_zero
          assert_equal(@time, TimeCalc.add_minutes(@time,))
      end

      def test_add_minute_ten
          assert_equal(" AM", TimeCalc.add_minutes(@time,))
      end

      def test_add_minute_thirteen
          assert_equal(" AM", TimeCalc.add_minutes(@time,))
      end

      def test_add_hour
          assert_equal(" AM", TimeCalc.add_minutes(@time,))
      end

      def test_add_two_hours_fifteen_minutes
          assert_equal(" AM", TimeCalc.add_minutes(@time,))
      end

      def test_add_past_meridiem
          # minutes = hours and minutes
          assert_equal(" PM", TimeCalc.add_minutes(@time,))
      end

      def test_alpha_hour_min_format_throws_exception
          assert_raise(ArgumentError) { TimeCalc.add_minutes("AB:CD AM",) }
      end

      def test_bad_meridiem_throws_exception
          assert_raise(ArgumentError) { TimeCalc.add_minutes("AB:CD TM",) }
      end

      def test_hr_greater_than_twelve
          assert_raise(ArgumentError) { TimeCalc.add_minutes(" PM",) }
      end

      def test_min_greater_than_fifty_nine
          assert_raise(ArgumentError) { TimeCalc.add_minutes(" PM",) }
      end

      def test_add_lot_of_minutes
        # minutes = hours and minutes
        assert_equal(" AM", TimeCalc.add_minutes(@time,))
      end

      def test_add_up_to_noon
        # AM plus hr min ()
        assert_equal(" PM", TimeCalc.add_minutes(@time,))
      end

      def test_add_whole_lot_of_minutes
        # minutes = hours and minutes
        assert_equal(" AM", TimeCalc.add_minutes(@time,))
      end

  end # end class TestTimeCalc

  class TimeCalc

      def self.add_minutes(time, minutes)
        (hour, min, meridiem) = parse_time_string(time)

        hour_increment = (min + minutes)/
        min_increment = (min + minutes)% - min

        while (hour + hour_increment >)
          meridiem = (meridiem == 'AM' ? 'PM' : 'AM')
          hour_increment -=
        end

        hour += hour_increment
        # special case forth hour
        meridiem = (meridiem == 'AM' ? 'PM' : 'AM') if hour ==
        min += min_increment

        hour.to_s + ":" + sprintf('%d', min) + " " + meridiem
      end

      private

      def self.parse_time_string(time)
          raise ArgumentError unless (matches = time.match(/(\d{,}):(\d{,})\s+(\w{})/))
          matches = time.match(/^(\d{,}):(\d{,})\s+([A|P]M)$/)
          hour = matches[].to_i
          min = matches[].to_i
          meridiem = matches[]
          raise ArgumentError unless (hour <=)
          raise ArgumentError unless (min <)
          return [hour, min, meridiem]
      end
  end # end class TimeCalc

 if __FILE__ == $
   puts TimeCalc.add_minutes(ARGV[], ARGV[].to_i)
 end