I don't know about the time for {.a, but this modification helps a bit
earlier on in the brute force process:
all=: {{ A#~x=".@>A=. ~. ,arith^:5 ":each y}}
Putting in a few diagnostics, I found in one run:
task ''
terms: 4 7 7 8 9 10
target: 315
┌─────┬──────┬──────┐
│size │934358│339567│
└─────┴──────┴──────┘
#solutions: 428
for example: ((7+(4+7))*(8+10))-9
... where size reports the dimension of A before and after taking its
nub, ~.
I'm afraid I didn't time that one, but taking the nub appears to have
saved
600 000 odd calculations out of 900 000 odd, as well as 600 000 odd
lines/boxes
of calculands.
Cheers,
Mike
On 09/10/2022 18:14, Raul Miller wrote:
https://rosettacode.org/wiki/Countdown#J
task''
terms: 4 7 8 9 10 10
target: 300
#solutions: 1213
for example: (10+(9*10))*((4+7)-8)
The #solutions line takes approaching 20 seconds. That's not the problem here.
The 'for example' line takes several seconds in J903 (and J904). And
the expression is
echo 'for example: ',;{.a
The only thing I can think of is that this time is occupied by garbage
collection.
FYI,
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