48 lines
1.2 KiB
Ada
48 lines
1.2 KiB
Ada
--
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-- Project Euler problem #2
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--
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-- Each new term in the Fibonacci sequence is generated by adding the previous
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-- two terms. By starting with 1 and 2, the first 10 terms will be:
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--
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-- 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...
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--
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-- By considering the terms in the Fibonacci sequence whose values do not
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-- exceed four million, find the sum of the even-valued terms.
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with Ada.Text_IO;
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use Ada.Text_IO;
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procedure Two is
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-- Upper bound of the Fibonacci sequence to consider
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Fib_Ceiling : constant Natural := 4_000_000;
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Fib_Previous : Natural := 0;
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Fib_Current : Natural := 1;
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Result : Natural := 0;
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function Is_Even (Number : in Natural) return Boolean is
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begin
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if (Number mod 2) = 0 then
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return true;
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else
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return false;
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end if;
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end Is_Even;
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begin
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while Fib_Current < Fib_Ceiling loop
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declare
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New_Value : Natural := Fib_Current + Fib_Previous;
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begin
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Fib_Previous := Fib_Current;
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Fib_Current := New_Value;
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if Is_Even (Fib_Current) then
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Result := (Result + Fib_Current);
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end if;
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end;
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end loop;
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Put_Line (Natural'Image (Result));
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end Two;
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