You are "holding on to the head". Try replacing "def perms" with "defn
perms []" and calling it when you start using it. That way the
permutations are let go as soon as they come. I noticed this with some
scripts that go through large files: it's really important to create
lazy longs sequences just for the one use and let them be garbage
collected right away.
Tuomas
On Mar 9, 6:47 pm, Dirk Vleugels <dirk.vleug...@gmail.com> wrote:
> I should re-test before post. This version of the main loop actually
> terminates (for smaller numbers), but will still blow up:
>
> (loop [ p (first perms) r (rest perms) s 0 c 0 ]
> (if (> c 8)
> s
> (if (every? #(%1 p) guards)
> (do
> (println p)
> (recur (first r) (rest r) (+ s (seq-to-val p)) (inc c)))
> (recur (first r) (rest r) s c))))
>
> Regards,
> Dirk
>
>
>
> On Mon, Mar 9, 2009 at 4:55 PM, Dirk Vleugels <dirk.vleug...@gmail.com> wrote:
> > Hi,
>
> > $ time clojure euler43.clj
> > (1 4 0 6 3 5 7 2 8 9)
> > (1 4 3 0 9 5 2 8 6 7)
> > (1 4 6 0 3 5 7 2 8 9)
> > java.lang.OutOfMemoryError: Java heap space
> > Dumping heap to java_pid7476.hprof ...
>
> > The hprof file is 330mb in size, i can't read it with jhat (even if i
> > give it 1.5G ....).
>
> > I assume perms is the problem, but i dont know how to write this in a
> > more memory efficient way - I'm not looking for a more efficient
> > algorithm though....
>
> > Thanx for any hint,
> > Dirk
>
> > (use 'clojure.contrib.combinatorics)
>
> > (def perms (permutations (range 10)))
>
> > (defn seq-to-val [ s ]
> > (reduce #(+ (* %1 10) %2) s))
>
> > (defn extract [ s i ]
> > (conj [] (nth s i) (nth s (inc i)) (nth s (inc (inc i)))))
>
> > (defn f24 [ s ]
> > (= (mod (seq-to-val (extract s 1)) 2) 0))
>
> > (defn f35 [ s ]
> > (= (mod (seq-to-val (extract s 2)) 3) 0))
>
> > (defn f46 [ s ]
> > (= (mod (seq-to-val (extract s 3)) 5) 0))
>
> > (defn f57 [ s ]
> > (= (mod (seq-to-val (extract s 4)) 7) 0))
>
> > (defn f68 [ s ]
> > (= (mod (seq-to-val (extract s 5)) 11) 0))
>
> > (defn f79 [ s ]
> > (= (mod (seq-to-val (extract s 6)) 13) 0))
>
> > (defn f810 [ s ]
> > (= (mod (seq-to-val (extract s 7)) 17) 0))
>
> > (def guards [ f24 f35 f46 f57 f68 f79 f810 ])
>
> > (loop [ p (first perms) r (rest perms) sum 0 count 0 ]
> > (when (= count 10)
> > sum)
> > (if (every? #(%1 p) guards)
> > (do
> > (println p)
> > (recur (first r) (rest r) (+ sum (seq-to-val p)) (inc count)))
> > (recur (first r) (rest r) sum (inc count))))
>
> --
> Dirk Vleugels
> 2scale GmbH
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