Day 20.0

ruby/day_20.rb

@@ -0,0 +1,14 @@
+require "prime"
+
+house = 1
+while true
+  house += 1
+
+  factors = house.prime_division
+  presents = factors.map {|f,x| (x+1).times.map {|i| f**i }.inject(:+) }.inject(:*)
+
+  if presents >= 3600000
+    puts house
+    exit
+  end
+end