rogerbraun · February 10, 2012 17:47 · Feb 10, 2012 · Feb 10, 2012
diff --git a/find_8001.rb b/find_8001.rb
@@ -1,9 +1,9 @@
 def check_number(n)
   n_f = 1.upto(n).inject(&:*)
-  quersumme = n_f.to_s.each_char.inject(0) do |res, v|
+  sum_of_digits = n_f.to_s.each_char.inject(0) do |res, v|
     res += v.to_i
   end
-  [n_f, quersumme]
+  [n_f, sum_of_digits]
 end
 
 found = false

diff --git a/find_8001.rb b/find_8001.rb
@@ -0,0 +1,16 @@
+def check_number(n)
+  n_f = 1.upto(n).inject(&:*)
+  quersumme = n_f.to_s.each_char.inject(0) do |res, v|
+    res += v.to_i
+  end
+  [n_f, quersumme]
+end
+
+found = false
+i = 1
+while not found do
+  res = check_number(i)
+  puts "Checking #{i}!, is #{res[0]}, sum of digits #{res[1]}"
+  i += 1
+  found = true if res[1] == 8001
+end
diff --git a/std_dev.rb b/std_dev.rb
@@ -0,0 +1,34 @@
+require "open-uri"
+require "nokogiri"
+
+url = "http://apply.embed.ly/static/data/2.html"
+
+doc = Nokogiri::HTML(open(url))
+
+article = doc.css("article").first
+
+def mark_depth(start, n)
+  if start.name == "p" then
+    res = n
+  else
+    res = nil
+  end
+
+  children = start.children.map do |child|
+    mark_depth(child, n+1)
+  end
+
+  [res, children].flatten.compact
+end
+
+res = mark_depth(article, 1)
+
+mean = res.inject(&:+) / res.count.to_f
+
+deviations = res.map{|n| (n - mean) * (n - mean)}
+
+deviations_avg = deviations.inject(&:+) / deviations.count.to_f
+
+std_dev = Math.sqrt(deviations_avg)
+
+puts std_dev
diff --git a/zipf.rb b/zipf.rb
@@ -0,0 +1,22 @@
+require "pry"
+nums = 1.upto(900)
+
+multiplier = nums.inject(&:+)
+
+frequencies = nums.each_with_index.map{|n, index| 
+  multiplier / (index + 1)
+}
+
+all = frequencies.inject(&:+)
+
+half = all / 2
+
+frequencies.each_with_index.inject(0) do |result, (value, index)|
+  result += value
+  if result >= half
+    puts index + 1
+    break
+  end
+  result
+end
+
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