2016 Update

Task/Factorial/Groovy/factorial-1.groovy

@@ -1,2 +1,2 @@
 def rFact
-rFact = { (it > 1) ? it * rFact(it - 1) : 1 }
+rFact = { (it > 1) ? it * rFact(it - 1) : 1 as BigInteger }

Task/Factorial/Groovy/factorial-2.groovy

@@ -1 +1 @@
-(0..6).each { println "${it}: ${rFact(it)}" }
+def iFact = { (it > 1) ? (2..it).inject(1 as BigInteger) { i, j -> i*j } : 1 }

Task/Factorial/Groovy/factorial-3.groovy

@@ -1 +1,17 @@
-def iFact = { (it > 1) ? (2..it).inject(1) { i, j -> i*j } : 1 }
+def time = { Closure c ->
+    def start = System.currentTimeMillis()
+    def result = c()
+    def elapsedMS = (System.currentTimeMillis() - start)/1000
+    printf '(%6.4fs elapsed)', elapsedMS
+    result
+}
+
+def dashes = '---------------------'
+print "   n!       elapsed time   "; (0..15).each { def length = Math.max(it - 3, 3); printf " %${length}d", it }; println()
+print "--------- -----------------"; (0..15).each { def length = Math.max(it - 3, 3); print " ${dashes[0..<length]}" }; println()
+[recursive:rFact, iterative:iFact].each { name, fact ->
+    printf "%9s ", name
+    def factList = time { (0..15).collect {fact(it)} }
+    factList.each { printf ' %3d', it }
+    println()
+}