lu-1.c 416 Bytes
for (int c0 = 1; c0 < n; c0 += 64)
  for (int c1 = c0 - 1; c1 <= n; c1 += 64)
    for (int c2 = c0; c2 <= n; c2 += 1) {
      for (int c3 = c0; c3 <= min(min(c0 + 63, c1 + 62), c2 - 1); c3 += 1)
        for (int c4 = max(c1, c3 + 1); c4 <= min(n, c1 + 63); c4 += 1)
          s1(c3, c4, c2);
      if (c0 + 63 >= c2)
        for (int c4 = max(c1, c2 + 1); c4 <= min(n, c1 + 63); c4 += 1)
          s0(c2, c4);
    }