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@papaver
Created February 10, 2012 21:19
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Embedly Programming Challenge
#!/usr/bin/env ruby -w
#------------------------------------------------------------------------------
# requires
#------------------------------------------------------------------------------
require 'open-uri'
#------------------------------------------------------------------------------
# Problem #1
#------------------------------------------------------------------------------
def problem_1
((0..1000).map{ |x| { :d => x, :v => (((1..x).inject:*).to_s.split('').map{ |d| d.to_i }.inject:+) } }).find_all{ |h| (h[:v] == 8001) }[0][:d]
end
#------------------------------------------------------------------------------
# Problem #2
#------------------------------------------------------------------------------
# Note: standard deviation code copied from:
# https://www.bcg.wisc.edu/webteam/support/ruby/standard_deviation
# Add methods to Enumerable, which makes them available to Array
module Enumerable
# sum of an array of numbers
def sum
return self.inject(0){|acc,i|acc+i}
end
# average of an array of numbers
def average
return self.sum/self.length.to_f
end
# variance of an array of numbers
def sample_variance
avg=self.average
sum=self.inject(0){|acc,i|acc+(i-avg)**2}
return(1/self.length.to_f*sum)
end
# standard deviation of an array of numbers
def standard_deviation
return Math.sqrt(self.sample_variance)
end
end # module Enumerable
#------------------------------------------------------------------------------
def problem_2
open('http://apply.embed.ly/static/data/2.html'){ |f| f.read }.split("\n").grep(/(<article>|<\/article>|<div>|<\/div>|<p>)/).inject({:i=>0, :l=>[]}) { |h,x| h[:i] += x =~ /(<article>|<div>)/ ? 1 : x =~ /(<\/article>|<\/div>)/ ? -1 : 0; h[:l] += [h[:i]] if x =~ /<p>/; h }[:l].standard_deviation
end
#------------------------------------------------------------------------------
# Problem #3
#------------------------------------------------------------------------------
def problem_3
([900*900]*900).zip(1..900).map{ |x| x[0]/x[1] }.inject([[0, 0]]){ |l,v| l += [[v,l[-1][1]+v]] }.reject{ |x| x[1] > 2988774 }.count
end
#------------------------------------------------------------------------------
# main
#------------------------------------------------------------------------------
puts "Problem #1: #{problem_1}"
puts "Problem #2: #{problem_2}"
puts "Problem #3: #{problem_3}"
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