2012/7/23 Mark Engelberg <[email protected]>
> As David was posting his code, I was wrapping up my own experimentation
> with how transients apply here. Mine is similar, but doesn't use pattern
> matching -- seems a bit faster:
>
>
> (defrecord Tree [h l r])
>
> (defn generate-tree [c]
> (when-let [s (seq c)]
> (let [lr (generate-tree (rest s))]
> (Tree. (first s) lr lr))))
>
> (defn to-list
> ([t] (persistent! (to-list t (transient []))))
> ([t b]
> (if t
> (let [b (to-list (:l t) b),
> b (conj! b (:h t)),
> b (to-list (:r t) b)]
> b)
> b)))
>
>
True,
and notice you can also drop records altogether:
(defn generate-tree [c]
(when-let [s (seq c)]
(let [lr (generate-tree (rest s))]
[(first s) lr lr])))
(defn to-list
([t] (persistent! (to-list t (transient []))))
([t b]
(if t
(let [b (to-list (t 1) b),
b (conj! b (t 0)),
b (to-list (t 2) b)]
b)
b)))
(defn tree [n]
(generate-tree (range 1 n)))
(let [t (tree 21)]
(dotimes [_ 10]
(time
(dotimes [_ 1]
(println (count (to-list t)))))))
1048575
"Elapsed time: 346.446 msecs"
1048575
"Elapsed time: 37.2 msecs"
1048575
"Elapsed time: 32.795 msecs"
1048575
"Elapsed time: 31.655 msecs"
1048575
"Elapsed time: 45.388 msecs"
1048575
"Elapsed time: 30.612 msecs"
1048575
"Elapsed time: 27.141 msecs"
1048575
"Elapsed time: 40.887 msecs"
1048575
"Elapsed time: 27.526 msecs"
1048575
"Elapsed time: 26.747 msecs"
nil
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