ahmedalhafoudh.rb

require "time"

# Author: Ahmed Al Hafoudh <alhafoudh@freevision.sk>
# Date:   2009-10-09

def average_time_of_day(times)
  last = Time.at(0) # keep last time
  cum = sum = 0 # cum -> day span cumulation
                # sum -> unixtime summary
  
  times.each do |t|
    tt = Time.parse(t) # get the Time class instance from the string
    cum += 86400 if tt < last # if the time we are just parsing is before the time we parsed last time increment the day span cumulation by one day
    sum += (tt + cum).to_i # sum the unixtime seconds
    last = tt # set the new last time
  end

  Time.at(sum / times.length).strftime("%I:%M%p").downcase # calculate average time and format the output
end

if __FILE__ == $0
  # Some simple test cases
  
  # Input values from the text
  puts average_time_of_day(["11:15pm", "12:03am", "11:30pm", "11:23pm" ,"11:48pm"])
  
  # Code example on the page
  puts average_time_of_day(["11:51pm", "11:56pm", "12:01am", "12:06am", "12:11am"])
  puts average_time_of_day(["6:41am", "6:51am", "7:01am"])
end