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User:Ledrug/bits: Difference between revisions
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Line 88:
#define PBITS (MAX_PRIME * 8 / 30 + 1)
pint next_prime(pint);
int is_prime(
void sieve(pint);
Line 126:
fwrite(pbits, 1, PBITS, fp);
fclose(fp);
}
int is_prime(xint x)
{
pint p;
if (x > 5) {
if (x < MAX_PRIME)
return pbits[x/30] & bit_pos[x % 30];
for (p = 2; p; p = next_prime(p))
if (x % p == 0) return 0;
return 1;
}
return x == 2 || x == 3 || x == 5;
}
Line 215 ⟶ 228:
init_primes();
po = (1LLU << p) - 1;
printf("2^%u - 1 = %llu = ", p, po);
fflush(stdout);
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