Oh yeah,
pf =. 'paswo','rdbce','fghik','lmnqt',:'uvxyz'
(thanks Ric)
Henry Rich
On 2/19/2011 11:39 AM, Henry Rich wrote:
> I worked on the easy part:
>
> pfr =. ((] (<"1@[ { ])~ ((0 1&(|."_1)&.|:@[)`(-"1 |.)@.(+./@]) =/) @
> ($@] #: (i.~ ,))) ];.0)~
>
> ; _2 pf&pfr\ 'allisdiscoveredfleex'
> pmqfabhwewzddrrgtrbz
>
> ; _2 (];.0 pf)&pfr\ 'pmqfabhwewzddrrgtrbz'
> allisdiscoveredfleex
>
> I can now add monad u;.0 to my Life List.
>
> (you would also need a preconditioner to handle double letters and
> odd-length input).
>
> I was hoping the same program would work for the hard part, but I wasn't
> sure what to do when the two letters match in more than one axis.
>
> Henry Rich
>
>
> On 2/19/2011 7:40 AM, Kip Murray wrote:
>> The Playfair cipher http://en.wikipedia.org/wiki/Playfair_cipher is based on
>> a 5
>> by 5 character array that treats i and j as equivalent:
>>
>> paswo
>> rdbce
>> fghik
>> lmnqt
>> uvxyz
>>
>> To encode “All is discovered flee” you replace pairs of letters
>> al li sd is co ve re df le ex with pairs diagonally opposite, one to the
>> right,
>> or one below (wrapping) from the table, getting
>>
>> pm qf ab hw ew zd dr rg tr bz
>>
>> Your mission, should you decide to accept it, is to write j code for
>> enciphering
>> and deciphering, given the five by five table. That’s the easy part. The
>> hard
>> part is to design and implement an analogous cipher that uses the 3 by 3 by 3
>> character array below to replace triples of letters alx _is _di sco ver ed_
>> fle ex_
>>
>> pas
>> wor
>> dbc
>>
>> efg
>> hij
>> klm
>>
>> nqt
>> uvx
>> yz_
>>
>> ----------------------------------------------------------------------
>> For information about J forums see http://www.jsoftware.com/forums.htm
>>
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
>
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
