Solve Josephus Problem Using Erlang

Josephus（约瑟夫）问题的数学方法

%%%----------------------------------------------------------------
%%% @author Genesislive <genesislive@126.com>
%%% 	[https://]
%%% @copyright 2013
%%% @doc josephus problem
%%% @end
%%%----------------------------------------------------------------
-module(josephus).

-export([josephus_it/2, josephus/2]).

%%-----------------------------------------------------------------
%% @doc solve josephus problem
%%		fun(1) = 0,	一个人；
%%		fun(n) = (fun(n - 1) + m) % n,  n个人
%% @spec josephus_it(N, M) -> integer()
%% where
%%  N:integer() number of people
%%  M:integer() mth people
%% @end
%%-----------------------------------------------------------------
josephus_it(1, _) -> 0;
josephus_it(N, M) ->
(josephus_it(N - 1, M) + M) rem N.

%%-----------------------------------------------------------------
%% @doc
%% @end
%%-----------------------------------------------------------------
josephus(N, M) ->
lists:foldl(fun(I, S) ->
% io:format("~p~n", [((S + M) rem I)]),
((S + M) rem I)
end, 0, lists:seq(2, N)).