I cannot comment on elegance, but I can disagree about the efficiency issue:
timespacex ',10#.(perms 7){"1/1+7 comb 9'
0.015591 2.15104e7
timespacex '10 #. (,/@:(],"1 0 -."1)^:6 ,.)1+i.9'
0.036695 3.7755e7
Thanks,
--
Raul
On Tue, Aug 15, 2017 at 9:53 AM, R.E. Boss <[email protected]> wrote:
> I suggest you use larger numbers for your performance tests.
>
> (10#.(#~(-:~.)"1) >: 9#.inv i. 9^6)-: 10 #.(,/@:(],"1 0 -."1)^:5 ,.)>:i.9
> 1
> ts'10#.(#~(-:~.)"1) >: 9#.inv i. 9^6'
> 0.39192919 1.7905766e8
> ts'10 #.(,/@:(],"1 0 -."1)^:5 ,.)>:i.9'
> 0.010126433 9442816
>
> The Groeneveld solution is more efficient by a factor of approx. 700 (38 *
> 19).
> Apart from being the most elegant.
>
>
> R.E. Boss
>
>
>> -----Original Message-----
>> From: Programming [mailto:[email protected]]
>> On Behalf Of 'Mike Day' via Programming
>> Sent: maandag 14 augustus 2017 22:01
>> To: [email protected]
>> Subject: Re: [Jprogramming] Quora problem
>>
>> Yes, much better!
>>
>> cf my suggestion a few days ago, and another constructive one using tap and
>> comb, q_tap_comb :
>>
>> ... time & space for Skip's original problem:
>> ts'10 #.(,/@:(],"1 0 -."1)^:2 ,.)>:i.9'NB. AG
>> 0.000120949 40448
>>
>> ts'10#.(#~(-:~.)"1) >: 9#.inv i. 9^3' NB. MD
>> 0.000774292 84608
>>
>> ts'q_tap_comb 3' NB. constructive, eg RM
>> 0.00130777 39424
>>
>> ... generating required numbers in [12345, 98765]:
>> ts'10 #.(,/@:(],"1 0 -."1)^:4 ,.)>:i.9'
>> 0.00548052 2.23386e6
>>
>> ts'10#.(#~(-:~.)"1) >: 9#.inv i. 9^5'
>> 0.066979 5.91731e6
>>
>> ts'q_tap_comb 5'
>> 0.0397513 2.11584e6
>>
>> where
>> q_tap_comb =: tap @[ ,@(10 #."1 {&.:|:) >:@comb&9 f.
>> ie
>> q_tap_comb
>> (i.@! A. i.)@[ ,@(10 #."1 {&.:|:) >:@(4 : 0)&9
>>
>> k=. i.>:d=.y-x
>>
>> z=. (d$<i.0 0),<i.1 0
>>
>> for. i.x do. z=. k ,.&.> ,&.>/\. >:&.> z end.
>>
>> ; z
>>
>> )
>>
>>
>> Thanks,
>> Mike
>>
>>
>> On 14/08/2017 18:16, Arie Groeneveld wrote:
>> > My version of variations (without repetitions) :
>> >
>> > 10 #. (,/@:(],"1 0 -."1)^:2 ,.)1+i.9
>> >
>> > More general:
>> >
>> > (3) 4 :'y,/@:(],"1 0 -."1)^:(x-1) ,.y' 'abcd'
>> >
>> >
>> > Op 12-08-17 om 11:16 schreef Skip Cave:
>> >> How can I use J to generate all the possible 3-digit integers that
>> >> can be constructed using the digits 1-9 (no zeros), with no repeated
>> >> digits in each integer? The sequence starts with 123 (smallest) and
>> >> goes to 987 (largest). Here's the first few integers in the sequence:
>> >>
>> >> 123 124 125 126 127 128 129 132 134 135 136 137 138 139 142 143 145
>> >> 146 147
>> >> 148 149 152 153 154 156 157 158 159 162......
>> >>
>> >> Skip
>> >>
>> >> Skip Cave
>> >> Cave Consulting LLC
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>>
>>
>>
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