59 lines
2.0 KiB
C
59 lines
2.0 KiB
C
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#include <stdio.h>
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#include <math.h>
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int main()
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{
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int limit;
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int wlimit;
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int i, j, k, x, y, z;
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unsigned char *sieb;
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printf("Please insert a number up to which all primes are calculated: ");
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scanf("%d", &limit);
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sieb = (unsigned char *) calloc(limit, sizeof(unsigned char));
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wlimit = sqrt(limit);
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for (x = 1; x <= wlimit; x++)
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{
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for (y = 1; y <= wlimit; y++)
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{
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z = 4 * x * x + y * y;
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if (z <= limit && (z % 60 == 1 || z % 60 == 13 || z % 60 == 17 || z
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% 60 == 29 || z % 60 == 37 || z % 60 == 41 || z % 60 == 49
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|| z % 60 == 53))
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{
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sieb[z] = !sieb[z];
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}
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z = 3 * x * x + y * y;
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if (z <= limit && (z % 60 == 7 || z % 60 == 19 || z % 60 == 31 || z
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% 60 == 43))
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{
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sieb[z] = !sieb[z];
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}
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z = 3 * x * x - y * y;
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if (x > y && z <= limit && (z % 60 == 11 || z % 60 == 23 || z % 60
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== 47 || z % 60 == 59))
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{
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sieb[z] = !sieb[z];
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}
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}
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}
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for (i = 5; i <= wlimit; i++)
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{
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if (sieb[i] == 1)
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{
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for (j = 1; j * i * i <= limit; j++)
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{
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sieb[j * i * i] = 0;
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}
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}
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}
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printf("The following primes have been calculated:\n2\n3\n5");
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for (i = 5; i <= limit; i++)
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{
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if (sieb[i] == 1)
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{
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printf("\n%d", i);
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}
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}
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scanf("%d", &i);
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return 0;
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}
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