46 строки
853 B
Plaintext
46 строки
853 B
Plaintext
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#! /usr/bin/env slsh
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% This demo counts the number of primes between 2 and some integer
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private define usage ()
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{
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() = fprintf (stderr, "Usage: %S <integer greater than 2>\n", __argv[0]);
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exit (1);
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}
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define count_primes (num)
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{
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variable size = (num - 1)/2;
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variable nonprimes = Char_Type[size + 1]; % last one is sentinel
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variable count = 1;
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variable prime = 3;
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variable i = 0;
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do
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{
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count++;
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%()=printf ("%S\n", prime);
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nonprimes [[i:size-1:prime]] = 1;
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variable i_save = i;
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while (i++, nonprimes[i])
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;
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prime += 2 * (i - i_save);
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}
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while (i < size);
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return count;
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}
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private variable Num;
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if (__argc != 2)
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usage ();
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Num = integer (__argv[1]);
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if (Num < 3)
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usage ();
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tic ();
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()=printf ("\n\n%d primes between 2 and %d in %f seconds.\n",
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count_primes (Num), Num, toc ());
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exit(0);
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