[Jprogramming] Permutations

[bill lam]

You may use monad ;: (word formation) to visualise how J interpreter parse
these two sentsences,
   ;: '/:~ :/:@": &.>y'
+--+-+-+--+-+--+--+-+-+
|/:|~|:|/:|@|":|&.|>|y|
+--+-+-+--+-+--+--+-+-+
   ;: '/:~:/:@": &.>y'
+--+--+--+-+--+--+-+-+
|/:|~:|/:|@|":|&.|>|y|
+--+--+--+-+--+--+-+-+

I short the : (and also .) must not separate from preceding characters
it the combined group should be treated as a single token.

Чтв, 29 Сен 2011, Linda Alvord писал(а):
> Here is the space that is bothering me.  The different results are dependent
> upon the space before the colon.
> 
>    d=: 13 : '/:~ :/:@": &.>y'
>    d a,b
> ------T-----┐
> │01123│01123│
> L-----+------
> 
>    e=: 13 : '/:~:/:@": &.>y'
>    e a,b
> 0 1
> 
>    
>    -----Original Message-----
> From: programming-bounces at jsoftware.com
> [mailto:programming-bounces at jsoftware.com] On Behalf Of David Mitchell
> Sent: Thursday, September 29, 2011 6:24 AM
> To: Programming forum
> Subject: Re: [Jprogramming] Permutations
> 
> I find this helpful to see differences:
> 
>     /:~ :/:@": &.>a,b
>                       -- ~ --- /:
>                 -- : -+- /:
>           -- @ -+- ":
>    -- &. -+- >
>    │
> --+      -- a
>    L------+- ,
>           L- b
> 
> 
>     /:~:([:/:": )&.>a,b
>    -- /:
>    │    -- ~:
>    │    │          -- [:
> --+    │      ----+- /:
>    │    +- &. -+   L- ":
>    L----+      L- >
>         │
>         │      -- a
>         L------+- ,
>                L- b
> 
> --
> David Mitchell
> 
> On 9/29/2011 5:45, Linda Alvord wrote:
> > The only difference between the correct and the incorrect result is a
> space
> > before the second  :  .   Should a space make a difference ever? In the
> > correct result I can't understand what it is, what it does and why it does
> > it.
> >
> >     /:~ :/:@":&.>a,b
> > ------T-----┐
> > │01123│01123│
> > L-----+------
> >
> >
> >     /:~:([:/:": )&.>a,b
> > 0 1
> >
> > Since I set out originally to remove "atop", how can I do it?
> >
> >    /:~ :([: /: ":)&.>a,b
> > ------T-----┐
> > │10123│32110│
> > L-----+------
> >
> > Hope you can help.  Thanks.  Linda
> >
> > -----Original Message-----
> > From: programming-bounces at jsoftware.com
> > [mailto:programming-bounces at jsoftware.com] On Behalf Of Ian Clark
> > Sent: Thursday, September 22, 2011 9:13 PM
> > To: Programming forum
> > Subject: Re: [Jprogramming] Permutations
> >
> > Off-the-cuff...
> >
> >     a=: 10123
> >     b=: 32110
> >     c=: 32100
> > -:/ /:~ :/:@":&.>   a,b
> > 1
> > -:/ /:~ :/:@":&.>   a,c
> > 0
> >
> >
> > On Thu, Sep 22, 2011 at 10:41 PM, David Vaughan
> > <purpleblues13 at googlemail.com>  wrote:
> >> Hi, what is the best (fastest) way to check whether a number is a
> > permutation of another number?
> >> I've tried listing all permutations of one number and checking whether
> the
> > other number is in the list of permutations. This seems pretty slow, so I
> > was hoping for a faster method.
> >>
> >> Thanks.
> >> ----------------------------------------------------------------------
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> >>
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> >
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> ----------------------------------------------------------------------
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> 
> ----------------------------------------------------------------------
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-- 
regards,
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