new exp

chapter_3/db.erl

@@ -0,0 +1,19 @@
+-module(db).
+-export([new/0, destroy/1, write/3, delete/2, read/2, match/2]).
+
+new() -> [].
+destroy(_Db) -> successful.
+
+write(Key, Val, Db) -> [{Key, Val} | Db].
+
+delete(_Key, []) -> [];
+delete(Key, [{HK, _}|T]) when Key == HK -> delete(Key, T);
+delete(Key, [H|T]) -> [H|delete(Key, T)].
+
+read(_Key, []) -> {error, instance};
+read(Key, [{H_Key, Val}|_T]) when Key == H_Key -> {ok, Val};
+read(Key, [_H|T]) -> read(Key, T).
+
+match(_Val, []) -> [];
+match(Val, [{H_Key, H_Val} | T]) when H_Val == Val -> [H_Key | match(Val, T)];
+match(Val, [_H|T]) -> match(Val, T).

chapter_3/list.erl

@@ -0,0 +1,17 @@
+-module(list).
+-compile(export_all).
+
+filter([], _N) -> [];
+filter([H|T], N) when H =< N -> [H | filter(T, N)];
+filter([_H|T], N) -> filter(T, N).
+
+reverse(List) -> reverse(List, []).
+
+% Good Job 要多使用尾递归
+reverse([], R) -> R;
+reverse([H|T], R) -> reverse(T, [H|R]).
+
+concatenate([], R) -> reverse(R);
+concatenate([[]|Ty], R) -> concatenate(Ty, R);
+concatenate([[H|Tx]|Ty], R) -> concatenate([Tx|Ty], [H|R]).
+

chapter_3/sort.erl

@@ -1,4 +1,21 @@
--module(sort)
--export([quick/1])
+-module(sort).
+-compile(export_all).
 
-qucik() -> .
+quick([]) -> [];
+
+quick([H|T]) -> 
+  [Max, Min] = quick_x(H, T, [], []),
+  flatten([quick(Max) | [H | quick(Min)]]).
+
+quick_x(_, [], Min, Max) ->
+  [Max, Min];
+
+quick_x(Cur, [H|T], Min, Max) when Cur < H ->
+  quick_x(Cur, T, Min, [H|Max]);
+
+quick_x(Cur, [H|T], Min, Max) when Cur >= H ->
+  quick_x(Cur, T, [H|Min], Max).
+
+flatten([]) -> 
+flatten([H|T]) ->
+  [H|flatten(T)].

chapter_4/ring.erl

@@ -0,0 +1,32 @@
+-module(ring).
+-export([loop/1, new_proc/1, new_proc/3]).
+
+new_proc(N) when N > 1 ->
+  FirstPid = spawn(ring, loop, [self()]),
+  new_proc(N - 1, FirstPid, FirstPid).
+
+new_proc(0, Pid, FirstPid) ->
+  FirstPid ! {loop, Pid},
+  register(ring_srv, FirstPid),
+  io:format("Successful create processes");
+
+new_proc(N, Pid, FirstPid) -> 
+  NewPid = spawn(ring, loop, [Pid]),
+  new_proc(N - 1, NewPid, FirstPid).
+
+
+
+loop(Pid) -> 
+  receive 
+    {loop, LastPid} ->
+      loop(LastPid);
+
+    {message, 1} -> 
+      io:format("~w receive a last message ~n", [self()]),
+      loop(Pid);
+
+    {message, Count} ->
+      io:format("~w receive a message ~w -> send ~w to ~w ~n", [self(), Count, Count - 1, Pid]),
+      Pid ! {message, Count - 1},
+      loop(Pid)
+  end.