Data commit

Task/Circular-primes/Prolog/circular-primes.pro

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+?- use_module(library(primality)).
+
+circular(N) :- member(N, [2, 3, 5, 7]).
+circular(N) :-
+    limit(15, (
+        candidate(N),
+        N > 9,
+        circular_prime(N))).
+circular(r(K)) :-
+    between(6, inf, K),
+    N is (10**K - 1) div 9,
+    prime(N).
+
+candidate(0).
+candidate(N) :-
+    candidate(M),
+    member(D, [1, 3, 7, 9]),
+    N is 10*M + D.
+
+circular_prime(N) :-
+    K is floor(log10(N)) + 1,
+    circular_prime(N, N, K).
+circular_prime(_, _, 0) :- !.
+circular_prime(P0, P, K) :-
+   P >= P0,
+   prime(P),
+   rotate(P, Q), succ(DecK, K),
+   circular_prime(P0, Q, DecK).
+
+rotate(N, M) :-
+    D is floor(log10(N)),
+    divmod(N, 10, Q, R),
+    M is R*10**D + Q.
+
+main :-
+    findall(P, limit(23, circular(P)), S),
+    format("The first 23 circular primes:~n~w~n", [S]),
+    halt.
+
+?- main.