shelling · November 27, 2014 14:14 · Nov 27, 2014
diff --git a/double-square-number.rb b/double-square-number.rb
@@ -0,0 +1,23 @@
+#!/usr/bin/env ruby
+
+def integer?(number)
+  (number % 1) == 0
+end
+
+def double_square_number?(number)
+  sqrt = Math.sqrt(number)
+  if integer?(sqrt)
+    [sqrt.to_i, 0]
+  else
+    sqrt.floor.downto(1) do |n|
+      if integer?(m = Math.sqrt(number - n ** 2))
+        return [n, m.to_i]
+      end
+    end
+    return false
+  end
+end
+
+for i in 1..104 do
+  puts "#{i} => #{double_square_number?(i).inspect}"
+end