USuserbinator·Apr 10, 2016
An even faster x86-64 Asm one that does it with no memory accesses - everything is in registers:
https://github.com/davidad/8queens/blob/1989666c45baa639f152...
In N-queen puzzle in 4 lines of Scaladavidad
8queens
Assembly2014–2016
davidad / 8queens
8queens
x64 assembler solution to n-queens problem. Not tested for n!=8.
4Distinct people
6Mentions
0Explicit recommenders
62GitHub stars
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What it is
x64 assembler solution to n-queens problem. Not tested for n!=8.
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This week on Hacker News
Nov 7–Nov 14 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/14/2026, 3:03:16 PM UTC.
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Mentions over time
HN mentions by month6 dated mentions
Observed mentions: 2014-02-26 01:36:19 UTC to 2016-04-10 16:38:47 UTC.
Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.
View mention counts and date ranges
| Period | Start (UTC) | End (exclusive, UTC) | Mentions | Submissions | Comments |
|---|---|---|---|---|---|
| Feb 2014 | 2014-02-01 00:00:00 UTC | 2014-03-01 00:00:00 UTC | 4 | 0 | 4 |
| Mar 2014 | 2014-03-01 00:00:00 UTC | 2014-04-01 00:00:00 UTC | 0 | 0 | 0 |
| Apr 2014 | 2014-04-01 00:00:00 UTC | 2014-05-01 00:00:00 UTC | 0 | 0 | 0 |
| May 2014 | 2014-05-01 00:00:00 UTC | 2014-06-01 00:00:00 UTC | 0 | 0 | 0 |
| Jun 2014 | 2014-06-01 00:00:00 UTC | 2014-07-01 00:00:00 UTC | 0 | 0 | 0 |
| Jul 2014 | 2014-07-01 00:00:00 UTC | 2014-08-01 00:00:00 UTC | 0 | 0 | 0 |
| Aug 2014 | 2014-08-01 00:00:00 UTC | 2014-09-01 00:00:00 UTC | 0 | 0 | 0 |
| Sep 2014 | 2014-09-01 00:00:00 UTC | 2014-10-01 00:00:00 UTC | 0 | 0 | 0 |
| Oct 2014 | 2014-10-01 00:00:00 UTC | 2014-11-01 00:00:00 UTC | 0 | 0 | 0 |
| Nov 2014 | 2014-11-01 00:00:00 UTC | 2014-12-01 00:00:00 UTC | 0 | 0 | 0 |
| Dec 2014 | 2014-12-01 00:00:00 UTC | 2015-01-01 00:00:00 UTC | 0 | 0 | 0 |
| Jan 2015 | 2015-01-01 00:00:00 UTC | 2015-02-01 00:00:00 UTC | 0 | 0 | 0 |
| Feb 2015 | 2015-02-01 00:00:00 UTC | 2015-03-01 00:00:00 UTC | 0 | 0 | 0 |
| Mar 2015 | 2015-03-01 00:00:00 UTC | 2015-04-01 00:00:00 UTC | 1 | 1 | 0 |
| Apr 2015 | 2015-04-01 00:00:00 UTC | 2015-05-01 00:00:00 UTC | 0 | 0 | 0 |
| May 2015 | 2015-05-01 00:00:00 UTC | 2015-06-01 00:00:00 UTC | 0 | 0 | 0 |
| Jun 2015 | 2015-06-01 00:00:00 UTC | 2015-07-01 00:00:00 UTC | 0 | 0 | 0 |
| Jul 2015 | 2015-07-01 00:00:00 UTC | 2015-08-01 00:00:00 UTC | 0 | 0 | 0 |
| Aug 2015 | 2015-08-01 00:00:00 UTC | 2015-09-01 00:00:00 UTC | 0 | 0 | 0 |
| Sep 2015 | 2015-09-01 00:00:00 UTC | 2015-10-01 00:00:00 UTC | 0 | 0 | 0 |
| Oct 2015 | 2015-10-01 00:00:00 UTC | 2015-11-01 00:00:00 UTC | 0 | 0 | 0 |
| Nov 2015 | 2015-11-01 00:00:00 UTC | 2015-12-01 00:00:00 UTC | 0 | 0 | 0 |
| Dec 2015 | 2015-12-01 00:00:00 UTC | 2016-01-01 00:00:00 UTC | 0 | 0 | 0 |
| Jan 2016 | 2016-01-01 00:00:00 UTC | 2016-02-01 00:00:00 UTC | 0 | 0 | 0 |
| Feb 2016 | 2016-02-01 00:00:00 UTC | 2016-03-01 00:00:00 UTC | 0 | 0 | 0 |
| Mar 2016 | 2016-03-01 00:00:00 UTC | 2016-04-01 00:00:00 UTC | 0 | 0 | 0 |
| Apr 2016 | 2016-04-01 00:00:00 UTC | 2016-05-01 00:00:00 UTC | 1 | 0 | 1 |
What Hacker News says
6 sources8queens – x64 assembler solution to n-queens problem
25 points · Open discussionWow! I like your C solution. I'm glad that at least the speedup is still measurable, but it's a close shave.
I implemented your "free 2x speedup" in asm [1]. Sure enough, solution time improved to 4.6us on my machine [2].
[1] https://github.com/davidad/8queens/commit/61119a7f0019e4a85e...
[2] https://github.com/davidad/8queens/tree/free-2x-speedup
In Overkilling the 8-queens ProblemAs an update I saw that the original post was about finding all the solutions to the problem, compared to the single first solution searched for above. Running for finding all solutions, I got the following timings (same computer as above, same settings, default consistency).
n time search tree solutions
8 0.8752 ms 767 92
10 14.2759 ms 11431 724
12 306.7616 ms 232163 14200
14 8782.4620 ms 6391931 365596
Downloading the c-versions from https://github.com/davidad/8queens/tree/%2Bc_comparison gives a reference-time using the time built-in command of around 750 ms for 10k iterations. This means that the C solver takes around 0.075 ms per iteration which is a factor of ten faster than the Gecode version. That is not unreasonable given that the Gecode versi
Read the rest
on is a high-level model in a general framework.
I did not manage to build the assembly-version unfortunately.
EDIT: Updated the timings and comments of the C-solver to represent that it actually solved the problem 10k times. Lesson, never do benchmarks quickly :-)
Here [1] is the comparison repository, for anyone interested.
[1] https://github.com/davidad/8queens/tree/%2Bc_comparison
EDIT: I don't seem to have -Ofast, but I added a note to the readme to ask people to try it. I also added the recommended flags for Sandy Bridge, i.e. -march=core2 -msse4.1 -msse4.2.
In Overkilling the 8-queens ProblemSee [1]; it is about a factor of 7 win vs. a reasonable C implementation.
[1] https://github.com/davidad/8queens/tree/%2Bc_comparison
In Overkilling the 8-queens Problem