Data commit

Task/Happy-numbers/Erlang/happy-numbers-1.erl

@@ -0,0 +1,32 @@
+-module(tasks).
+-export([main/0]).
+-import(lists, [map/2, member/2, sort/1, sum/1]).
+
+is_happy(X, XS) ->
+    if
+	X == 1 ->
+	    true;
+	X < 1 ->
+	    false;
+	true ->
+	    case member(X, XS) of
+		true -> false;
+		false ->
+		    is_happy(sum(map(fun(Z) -> Z*Z end,
+				     [Y - 48 || Y <- integer_to_list(X)])),
+			     [X|XS])
+	    end
+    end.
+
+main(X, XS) ->
+    if
+	length(XS) == 8 ->
+	    io:format("8 Happy Numbers: ~w~n", [sort(XS)]);
+	true ->
+	    case is_happy(X, []) of
+		true -> main(X + 1, [X|XS]);
+		false -> main(X + 1, XS)
+	    end
+    end.
+main() ->
+    main(0, []).

Task/Happy-numbers/Erlang/happy-numbers-2.erl

@@ -0,0 +1 @@
+erl -run tasks main -run init stop -noshell

Task/Happy-numbers/Erlang/happy-numbers-3.erl

@@ -0,0 +1 @@
+8 Happy Numbers: [1,7,10,13,19,23,28,31]

Task/Happy-numbers/Erlang/happy-numbers-4.erl

@@ -0,0 +1,18 @@
+-module(tasks).
+
+-export([main/0]).
+
+main() -> io:format("~w ~n", [happy_list(1, 8, [])]).
+
+happy_list(_, N, L) when length(L) =:= N -> lists:reverse(L);
+happy_list(X, N, L) ->
+	Happy = is_happy(X),
+	if Happy -> happy_list(X + 1, N, [X|L]);
+	true -> happy_list(X + 1, N, L) end.
+
+is_happy(1) -> true;
+is_happy(4) -> false;
+is_happy(N) when N > 0 ->
+	N_As_Digits = [Y - 48 || Y <- integer_to_list(N)],
+	is_happy(lists:foldl(fun(X, Sum) -> (X * X) + Sum end, 0, N_As_Digits));
+is_happy(_) -> false.