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Clojure list reduction #2

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Clojure list reduction #2

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34e55ef
remove a count
scientific-coder Aug 18, 2011
81c3104
custom recursive Clojure code
scientific-coder Aug 18, 2011
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24 changes: 17 additions & 7 deletions list-reduction/josephus.clj
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Original file line number Diff line number Diff line change
@@ -1,13 +1,23 @@
(defn shout [counter nth coll]
(if (== (count coll) 1)
(defn shout
([nth coll] (let [to-kill (dec nth)] (shout to-kill to-kill coll)))
([counter to-kill coll]
(if (empty? (rest coll))
(first coll)
(shout
(rem (+ counter (count coll)) nth)
nth
(keep-indexed #(if(not= 0 (rem (+ %1 counter) nth)) %2) coll))))
(let [[next-counter next-coll]
(loop [current-idx counter
to-process coll
res []]
(if (empty? to-process)
[current-idx res]
(if (== current-idx to-kill)
(recur 0 (rest to-process) res)
(recur (unchecked-inc current-idx)
(rest to-process)
(conj res (first to-process))))))]
(recur next-counter to-kill next-coll)))))

(defn josephus [people nth]
(shout 0 nth (range 1 (inc people))))
(shout nth (range 1 (inc people))))

;(defn countdown [iterations]
; (dotimes [_ iterations]
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