first commit

1 files changed, 40 insertions, 0 deletions

diff --git a/problem41.erl b/problem41.erl
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index 0000000..b221d36
--- /dev/null
+++ b/problem41.erl
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+-module(problem41).
+-export([solve/0]).
+
+solve() ->
+	Pan = gen_perms(),
+	Pri = gen_primes([2,3]),
+	lists:max([X || X <- Pan, lists:member(X, Pri)]).
+
+gen_perms() -> [list_to_integer(X) || X <- perms("123456789")].
+
+perms([]) -> [[]];
+perms(L) -> [[H|T] || H <- L, T <- perms(L--[H])].
+
+gen_primes(L) ->
+	if
+		hd(L) > 987654321 ->
+			tl(L);
+		true ->
+			gen_primes(gen_next(L))
+	end.
+gen_next(List) ->
+	gen_next(List, lists:max(List) + 1).
+gen_next(List, Next) ->
+	Q = will_divide(Next, List),
+	if
+		Q ->
+			gen_next(List, Next + 1);
+		true ->
+			[Next|List]
+	end.
+
+will_divide(_, []) ->
+	false;
+will_divide(Num, [H|T]) ->
+	if
+		Num rem H =:= 0 ->
+			true;
+		true ->
+			will_divide(Num, T)
+	end.