1 files changed, 17 insertions, 0 deletions
diff --git a/gcd.rb b/gcd.rb
new file mode 100755
index 0000000..0eefe8a
--- /dev/null
+++ b/gcd.rb
@@ -0,0 +1,17 @@
+#!/usr/bin/env ruby
+
+def gcd2 a, b
+    if b == 0
+        a
+    else
+        gcd2 b, a % b
+    end
+end
+
+# http://railspikes.com/2008/8/11/understanding-map-and-reduce
+def gcdn ns
+    ns.reduce{ |a, b| gcd2 a, b }
+end
+
+puts gcdn ARGV.collect{|s| s.to_i}
+