Data commit

Task/Sierpinski-triangle/Clojure/sierpinski-triangle.clj

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+(ns example
+  (:require [clojure.contrib.math :as math]))
+
+; Length of integer in binary
+; (copied from a private multimethod in clojure.contrib.math)
+(defmulti #^{:private true} integer-length class)
+
+(defmethod integer-length java.lang.Integer [n]
+  (count (Integer/toBinaryString n)))
+(defmethod integer-length java.lang.Long [n]
+  (count (Long/toBinaryString n)))
+(defmethod integer-length java.math.BigInteger [n]
+  (count (.toString n 2)))
+
+(defn sierpinski-triangle [order]
+  (loop [size (math/expt 2 order)
+         v    (math/expt 2 (- size 1))]
+    (when (pos? size)
+      (println
+       (apply str (map #(if (bit-test v %) "*" " ")
+		       (range (integer-length v)))))
+      (recur
+       (dec size)
+       (bit-xor (bit-shift-left v 1) (bit-shift-right v 1))))))
+
+(sierpinski-triangle 4)