Kolakoski sequence: Difference between revisions

=={{header|J}}==

<lang J>

NB. cyclic

create_cycle_=: 3 :0

I=: 0

A=: y

N=: # A

)

next_cycle_=: 3 :0

r=. A {~ N | I

I=: >: I

r

)

NB. kolakoski

kolakoski =: 30&$: :(dyad define) NB. TERMS kolakoski ALPHABET

c=. y conew'cycle'

s=. i. 0

term=. 0

while. x > # s do.

s=. (, ([: #~ next__c)`(term&{ # next__c)@.(term < #)) s

term=. >: term

end.

s

)

test=: (({.~ #) -: ]) }:@:(#;.1~ (1 , 2&(~:/\)))

</lang>

test cuts the data at a vector of frets where successive pairs are unequal. The groups are tallied, giving run length.

<pre>

f=: (;~ test)@:kolakoski

(; f)&> 1 2 ; 2 1 ; 1 3 1 2 ; 1 3 2 1

┌───────┬─┬─────────────────────────────────────────────────────────────┐

│1 2 │1│1 2 2 1 1 2 1 2 2 1 2 2 1 1 2 1 1 2 2 1 2 1 1 2 1 2 2 1 1 2 │

├───────┼─┼─────────────────────────────────────────────────────────────┤

│2 1 │1│2 2 1 1 2 1 2 2 1 2 2 1 1 2 1 1 2 2 1 2 1 1 2 1 2 2 1 1 2 1 1│

├───────┼─┼─────────────────────────────────────────────────────────────┤

│1 3 1 2│1│1 3 3 3 1 1 1 2 2 2 1 3 1 2 2 1 1 3 3 1 2 2 2 1 3 3 1 1 2 1 │

├───────┼─┼─────────────────────────────────────────────────────────────┤

│1 3 2 1│0│1 3 3 3 2 2 2 1 1 1 1 1 3 3 2 2 1 1 3 2 1 1 1 1 3 3 3 2 2 1 1│

└───────┴─┴─────────────────────────────────────────────────────────────┘

</pre>