Find squares n where n+1 is prime: Difference between revisions
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=={{header|Delphi}}== |
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{{works with|Delphi|6.0}} |
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{{libheader|SysUtils,StdCtrls}} |
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<syntaxhighlight lang="Delphi"> |
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function IsPrime(N: integer): boolean; |
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{Fast, optimised prime test} |
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var I,Stop: integer; |
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begin |
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if (N = 2) or (N=3) then Result:=true |
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else if (n <= 1) or ((n mod 2) = 0) or ((n mod 3) = 0) then Result:= false |
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else |
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begin |
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I:=5; |
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Stop:=Trunc(sqrt(N)); |
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Result:=False; |
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while I<=Stop do |
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begin |
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if ((N mod I) = 0) or ((N mod (I + 2)) = 0) then exit; |
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Inc(I,6); |
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end; |
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Result:=True; |
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end; |
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end; |
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procedure ShowPrimeSquares(Memo: TMemo); |
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var N,S2: integer; |
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begin |
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for N:= 1 to Trunc(sqrt(1000-1)) do |
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begin |
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S2:=N*N; |
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if IsPrime(S2+1) then Memo.Text:=Memo.Text+' '+IntToStr(S2); |
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end; |
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end; |
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</syntaxhighlight> |
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{{out}} |
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<pre> |
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1 4 16 36 100 196 256 400 576 676 |
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</pre> |
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=={{header|F_Sharp|F#}}== |
=={{header|F_Sharp|F#}}== |