77 lines
1.3 KiB
Markdown
77 lines
1.3 KiB
Markdown
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###Sieve of Erasthothenes
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Calculates the primes between 0 and 19200 with the sieve of Erasthothenes
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```textfunge
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program SieveOfEratosthenes : display[240, 80]
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begin
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// Init all Fields with '?'
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init();
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// Set an 'X' to every Primenumberfield
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calculate();
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// Output the primes
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output();
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end
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void init()
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var
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int i;
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begin
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for(i = 0; i < DISPLAY_SIZE; i++) do
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display[i % DISPLAY_WIDTH, i / DISPLAY_WIDTH] = '?';
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end
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display[0, 0] = ' ';
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display[1, 0] = ' ';
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end
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void calculate()
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var
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int i;
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begin
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for(i = 2; i < DISPLAY_SIZE; i++) do
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doNumber(i);
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end
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end
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void doNumber(int i)
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var
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char c;
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begin
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c = display[i % DISPLAY_WIDTH, i / DISPLAY_WIDTH];
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if (c == 'X' || c == ' ') then
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return;
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elsif (c == '?') then
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display[i % DISPLAY_WIDTH, i / DISPLAY_WIDTH] = 'X';
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clear(i);
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end
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end
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void clear(int n)
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var
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int p;
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begin
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for(p = 2*n; p < DISPLAY_SIZE; p += n) do
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display[p % DISPLAY_WIDTH, p / DISPLAY_WIDTH] = ' ';
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end
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end
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void output()
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var
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int i;
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begin
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out "Prime Numbers:\r\n";
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for(i = 2; i < DISPLAY_SIZE; i++) do
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if (display[i % DISPLAY_WIDTH, i / DISPLAY_WIDTH] == 'X') then
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outf i, "\r\n";
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end
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end
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end
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end
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```
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> **Note:** *This and other examples are included in the BefunGen download*
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