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Tail recursive erlang
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-module(trecursive). | |
-export([fib/1,perfect/1,test/0]). | |
fib(X) -> fib(X,0,1). | |
fib(0,Acc1,_) -> | |
Acc1; | |
fib(X,Acc1,Acc2) when X >= 1 -> | |
fib(X-1,Acc2,Acc1 + Acc2). | |
%Steep by steep: | |
%fib(4) -> fib(4,0,1). | |
%fib(4,0,1) -> fib(3,1,0 + 1). | |
%fib(3,1,1) -> fib(2,1,1 + 1). | |
%fib(2,1,2) -> fib(1,2,1 + 2). | |
%fib(1,2,3) -> fib(0,3,3 + 2). | |
%fib(0,3,5) -> 3. | |
perfect(X) -> perfect(X,1,0). | |
%Moddifeid according to brujoBenavides review: | |
%perfect(X,Divisor,Acc) when X == Divisor andalso X == Acc -> | |
perfect(X,X,X) -> | |
true; | |
%perfect(X,Divisor,_) when X == Divisor -> | |
perfect(X,X,_) -> | |
false; | |
perfect(X,Divisor,Acc) when X rem Divisor == 0 -> | |
perfect(X,Divisor +1 ,Acc + Divisor); | |
perfect(X,Divisor,Acc) -> | |
perfect(X,Divisor +1 ,Acc). | |
test() -> | |
3 = fib(4), | |
true = perfect(6), | |
true = perfect(28), | |
false = perfect(10), | |
success. |
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Yeah, thank you! I missed that.