40 lines
1.1 KiB
Ada
40 lines
1.1 KiB
Ada
--
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-- Project Euler problem #10
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--
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-- The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.
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--
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-- Find the sum of all the primes below two million.
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--
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with Ada.Numerics.Elementary_Functions,
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Ada.Text_IO;
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use Ada.Numerics.Elementary_Functions,
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Ada.Text_IO;
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procedure Ten is
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subtype Long_Natural is Long_Integer range 0 .. Long_Integer'Last;
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Ceiling : constant Natural := 2_000_000;
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Result : Long_Natural := 0;
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function Is_Prime (Input : in Natural) return Boolean is
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-- Using the "Trial Division" method detailed in this Wikipedia entry:
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-- https://secure.wikimedia.org/wikipedia/en/wiki/Prime_number#Trial_division
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Boundary : constant Natural := Natural (Sqrt (Float (Input)));
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begin
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for Index in 2 .. Boundary loop
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if (Input mod Index) = 0 then
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return false;
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end if;
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end loop;
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return true;
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end Is_Prime;
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begin
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for Index in 2 .. Ceiling loop
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if Is_Prime (Index) then
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Result := (Result + Long_Natural (Index));
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end if;
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end loop;
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Put_Line ("Sum of all primes:" & Long_Natural'Image (Result));
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end Ten;
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