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viniciusd/tail_recursion.erl

Created May 25, 2020 14:06
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tail_recursion.erl
-module(tail_recursion).
-export([is_perfect/1]).
is_perfect(N) ->
2*N == lists:sum(divisors(N)).
divisors(N) ->
divisors(N, 1, []).
divisors(N, I, ACC) when I*I < N andalso N rem I == 0 ->
divisors(N, I+1, [I|[N div I|ACC]]);
divisors(N, I, ACC) when I*I == N andalso N rem I == 0 ->
divisors(N, I+1, [I|ACC]);
divisors(N, I, ACC) when I*I =< N ->
divisors(N, I+1, ACC);
divisors(_N, _I, ACC) ->
ACC.
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