Created
May 20, 2020 10:28
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Tail recursion, perfect numbers. https://www.futurelearn.com/courses/functional-programming-erlang/3/steps/488098/
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| -module(perfect). | |
| -export([perfect/1]). | |
| perfect(N) -> | |
| perfect(N, 2, 1). | |
| perfect(N, D, Sum) when D * 2 < N, Sum < N -> | |
| if | |
| N rem D =:= 0 -> | |
| perfect(N, D + 1, Sum + D + N div D); | |
| true -> | |
| perfect(N, D + 1, Sum) | |
| end; | |
| perfect(N, _D, Sum) -> | |
| N =:= Sum. |
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