106 lines
1.7 KiB
ObjectPascal
106 lines
1.7 KiB
ObjectPascal
program Chowla_numbers;
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{$IFDEF FPC}
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{$MODE Delphi}
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{$ELSE}
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{$APPTYPE CONSOLE}
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{$ENDIF}
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uses
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SysUtils
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{$IFDEF FPC}
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,StrUtils{for Numb2USA}
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{$ENDIF}
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;
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{$IFNDEF FPC}
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function Numb2USA(const S: string): string;
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var
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I, NA: Integer;
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begin
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I := Length(S);
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Result := S;
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NA := 0;
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while (I > 0) do
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begin
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if ((Length(Result) - I + 1 - NA) mod 3 = 0) and (I <> 1) then
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begin
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Insert(',', Result, I);
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Inc(NA);
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end;
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Dec(I);
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end;
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end;
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{$ENDIF}
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function Chowla(n: NativeUint): NativeUint;
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var
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Divisor, Quotient: NativeUint;
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begin
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result := 0;
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Divisor := 2;
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while sqr(Divisor) < n do
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begin
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Quotient := n div Divisor;
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if Quotient * Divisor = n then
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inc(result, Divisor + Quotient);
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inc(Divisor);
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end;
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if sqr(Divisor) = n then
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inc(result, Divisor);
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end;
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procedure Count10Primes(Limit: NativeUInt);
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var
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n, i, cnt: integer;
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begin
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writeln;
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writeln(' primes til | count');
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i := 100;
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n := 2;
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cnt := 0;
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repeat
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repeat
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// Ord (true) = 1 ,Ord (false) = 0
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inc(cnt, ORD(chowla(n) = 0));
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inc(n);
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until n > i;
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writeln(Numb2USA(IntToStr(i)): 12, '|', Numb2USA(IntToStr(cnt)): 10);
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i := i * 10;
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until i > Limit;
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end;
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procedure CheckPerf;
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var
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k, kk, p, cnt, limit: NativeInt;
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begin
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writeln;
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writeln(' number that is perfect');
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cnt := 0;
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limit := 35000000;
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k := 2;
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kk := 3;
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repeat
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p := k * kk;
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if p > limit then
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BREAK;
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if chowla(p) = (p - 1) then
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begin
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writeln(Numb2USA(IntToStr(p)): 12);
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inc(cnt);
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end;
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k := kk + 1;
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inc(kk, k);
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until false;
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end;
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var
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I: integer;
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begin
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for I := 2 to 37 do
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writeln('chowla(', I: 2, ') =', chowla(I): 3);
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Count10Primes(10 * 1000 * 1000);
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CheckPerf;
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end.
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