Initial data commit

Task/Verhoeff-algorithm/J/verhoeff-algorithm-1.j

@@ -0,0 +1,30 @@
+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