RosettaCodeData/Task/Fibonacci-sequence/Mercury/fibonacci-sequence-4.mercury
2023-07-01 13:44:08 -04:00

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:- pragma memo(fib/2).
:- pred fib(int::in, int::out) is det.
fib(N, X) :-
( if N =< 2
then X = 1
else fib(N - 1, A), fib(N - 2, B), X = A + B ).