I actually pasted the wrong code here:
(defn count-num-chars [^String s]
(let [len (.length s)
space (int 32)]
(loop [i (int 0), c (int 0)]
(if (< i len)
(recur
(inc i)
(if (== (int (.charAt s i)) space)
c
(unchecked-inc c)))
c))))
On Dec 22, 12:19 pm, Rayne <[email protected]> wrote:
> chouser wrote a solution earlier. I and a buddy modified it (a very
> little) bit and managed to get it pretty blazing:
>
> ra...@ubuntu:~$ cake run ~/challenge.clj
> Chars outputted: 460
> Time (in nanoseconds): 5768.677
>
> Here is the function:
>
> (defn count-num-chars [^String s]
> (let [len (.length s)
> space (int 32)]
> (loop [i (int 0), c (int 0)]
> (if (< i len)
> (recur
> (inc i)
> (if (== (.codePointAt s i) space)
> c
> (unchecked-inc c)))
> c))))
>
> On Dec 22, 11:52 am, Rayne <[email protected]> wrote:
>
>
>
> > I have a piece of code, and I'd like to see how fast it can be.
>
> > (defn count-num-chars [^String s]
> > (loop [s s acc 0]
> > (if (seq s)
> > (recur (rest s) (if (= (first s) \space) acc (inc acc)))
> > acc)))
>
> > This is the fastest I've been able to get it. The function is very
> > simple. It takes a string and counts the number of non-space
> > characters inside of that string.
>
> > I've been testing this code against a 460 non-space character string.
> > Here is the entire source, benchmarking and all:
>
> > (def s (apply str (repeat 20 "This is a really long string")))
>
> > (defn count-num-chars [^String s]
> > (loop [s s acc 0]
> > (if (seq s)
> > (recur (rest s) (if (= (first s) \space) acc (inc acc)))
> > acc)))
>
> > (println "Chars outputted:" (count-num-chars s))
>
> > (let [before (System/nanoTime)]
> > (dotimes [_ 1000]
> > (count-num-chars s))
> > (let [after (System/nanoTime)]
> > (println "Time (in nanoseconds):" (/ (- after before) 1000.0))))
>
> > Running it gives me around 137343.295 nanoseconds. I've seen some Java
> > algorithms that could run at just under 3000 nanoseconds.
>
> > Hide your children and hide your women; I want to see the direst,
> > nastiest, rawest, fastest possible implementation of this function.
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