[Warren Pease]

I was hanging out with a friend and his new GF the other day, enjoying a couple of drinks. She asked me what my birthday was and I told her - she did some quick math and decided that I wasn't 'lucky'. Both her and my friend were; in that the sum of their birthday's month, date and year added up to 100 ex. 3/22/75.

I pointed out that it should really be 2000 and that this was one of the stupidest idea I had heard - determining luck based on numbers. Anyhow, the problem of determining this intrigued me. I had picked up a Ruby book earlier that week and in the course of a couple hours wrote this script that does exactly that - finds all dates that add up to a given number.

Here is the code:

Code:
#!/usr/bin/env ruby -wKU
require 'date'

start_time = Time.now

if ARGV.length != 1
  puts 'please provide the target number (and only the target number)'
else
  target = ARGV[0].to_i # this is a String initially
  start_year = target - 12 - 31 # maximum month and date for start year for target
  end_year = target - 1 - 1 # minimum month and date for end year for target
  n = 0 # just a counter
  (start_year..end_year).each do |year| 
    test_date = Date.new(year, 1, 1) # start with lowest possible value
    last_of_the_year = Date.new(year, 12, 31) # don't move up through to the next year
    hit_dates = Array.new
    while (last_of_the_year >= test_date) do
      if ( (test_date.year + test_date.month + test_date.day) == target )
        hit_dates << test_date 
        n = n + 1
      end
      test_date = (test_date + 1)
    end
    dates = hit_dates.collect { |d| d.month.to_s + '/' + d.day.to_s }
    dates = dates.join ', '
    puts hit_dates[0].year.to_s + ' ' + dates.to_s + ' (n:' + hit_dates.length.to_s + ')'  unless hit_dates.empty?
  end
  puts n.to_s + ' total dates which add up to ' + target.to_s
end

puts (Time.now - start_time).to_s + ' seconds'

And it's run from the command line:

Code:
./numbers.rb 2000

As this is one of the first Ruby scripts I've written, I wanted to see what people thought of it - where I could 'optimize' my code, see if there were any ruby tricks that I could use, better code design, etc. in order to learn from the exercise.

[mr.flow3r]

neat idea
I don't like the idea that if your birthday adds up to 100, it's a good luck however... because mine doesnt xD