rock papper scissor

rps.erl

-module(rps).
-export([tournament/2]).


beat(rock) -> paper;
beat(paper) -> scissors;
beat(scissors) -> rock.


result({X,X},Acc) -> Acc;
result({X,Y},Acc) ->
	case beat(X) == Y of
	     true -> Acc - 1;
	     false ->  Acc + 1
	end.

tournament(L,M) ->
	lists:foldl(fun result/2,0,lists:zip(L,M)).


%7> rps:tournament([rock,rock,paper,paper],[rock,paper,scissors,rock]).
%-1
%8> rps:tournament([rock,rock,paper,paper,rock],[rock,paper,scissors,rock,paper]).
%-2
%9>
%