Verhoeff algorithm: Difference between revisions

=={{header|J}}==

Implementation:

<lang J>cyc=: | +/~@i. NB. cyclic group, order y

ac=: |(+-/~@i.) NB. anticyclic group, order y

a2n=: (+#)@ NB. add 2^n

di=: (cyc,.cyc a2n),((ac a2n),.ac)

D=: di 5

INV=: ,I.0=D

P=: {&(C.1 5 8 9 4 2 7 0;3 6)^:(i.8) i.10

verhoeff=: {{

c=. 0

for_N. |.10 #.inv y do.

c=. D{~<c,P{~<(8|N_index),N

end.

}}

traceverhoeff=: {{

r=. EMPTY

c=. 0

for_N. |.10 #.inv y do.

c0=. c

c=. D{~<c,p=.P{~<(j=.8|N_index),N

r=. r, c,p,j,N_index,N,c0

end.

labels=. cut 'cᵢ p[i,nᵢ] i nᵢ n cₒ'

1 1}.}:~.":labels,(<;._1"1~[:*/' '=])' ',.":r

}}

checkdigit=: INV {~ verhoeff@*&10

valid=: 0 = verhoeff</lang>

Task examples:

<lang J> checkdigit 236 12345 123456789012

3 1 0

valid 2363

1

valid 123451

1

valid 1234567890120

1

valid 2369

0

valid 123459

0

valid 1234567890129

0

traceverhoeff 2363

cᵢ│p[i,nᵢ]│i│nᵢ│n│cₒ│

──┼───────┼─┼──┼─┼──┤

3 │3 │0│0 │3│0 │

1 │3 │1│1 │6│3 │

4 │3 │2│2 │3│1 │

0 │1 │3│3 │2│4 │

traceverhoeff 123451

cᵢ│p[i,nᵢ]│i│nᵢ│n│cₒ│

──┼───────┼─┼──┼─┼──┤

1 │1 │0│0 │1│0 │

9 │8 │1│1 │5│1 │

2 │7 │2│2 │4│9 │

8 │6 │3│3 │3│2 │

3 │5 │4│4 │2│8 │

0 │2 │5│5 │1│3 │

</lang>