Beta release. Problem Forge is new and open by invitation. The beta test period runs through 2026-11-30; the full opening is on 2026-12-01 00:00 UTC. Things may break, and we may correct the boards when they do. The difficulty of some rungs may be wrong. There are no prizes during the beta, and the bounty is not open. Your account and your progress stay when the beta ends. Please tell us what goes well and what goes wrong: admin@problemforge.com.

Firsts — November 2026

One First per rung from 01 to 12: whoever sends the first accepted answer to any copy of it that month. Quickest, average and median time run from a climber's first download of the rung to the accepted answer. Opened by counts the climbers who pressed Show this problem on the rung, downloaded it or solved it that month; percent solved is the share of them who solved it. From the 2026-11 month on, staff are not counted. Firsts do not change your score.

Boolean Satisfiability (SAT)

rungFirst solvedQuickest timeAverage timeMedian timeOpened byPercent solved
01
2026-11-SAT-01		 Lazy Subtour Cut
2026-11-01 00:45 UTC		 Lazy Subtour Cut
0:00		 0:00 0:00 1 100 %
02
2026-11-SAT-02		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:01		 0:01 0:01 1 100 %
03
2026-11-SAT-03		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:01		 0:01 0:01 1 100 %
04
2026-11-SAT-04		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:05		 0:05 0:05 1 100 %
05
2026-11-SAT-05		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:24		 0:24 0:24 1 100 %
06
2026-11-SAT-06		 Lazy Subtour Cut
2026-11-01 00:56 UTC		 Lazy Subtour Cut
9:01		 9:01 9:01 1 100 %
07
2026-11-SAT-07		 Lazy Subtour Cut
2026-11-01 01:02 UTC		 Lazy Subtour Cut
6:01		 6:01 6:01 1 100 %
08
2026-11-SAT-08		 Lazy Subtour Cut
2026-11-01 22:49 UTC		 Lazy Subtour Cut
21:47:14		 21:47:14 21:47:14 1 100 %

3-SAT

rungFirst solvedQuickest timeAverage timeMedian timeOpened byPercent solved
01
2026-11-3SAT-01		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:00		 0:00 0:00 1 100 %
02
2026-11-3SAT-02		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:00		 0:00 0:00 1 100 %
03
2026-11-3SAT-03		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:00		 0:00 0:00 1 100 %
04
2026-11-3SAT-04		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:04		 0:04 0:04 1 100 %
05
2026-11-3SAT-05		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:13		 0:13 0:13 1 100 %
06
2026-11-3SAT-06		 Lazy Subtour Cut
2026-11-01 00:52 UTC		 Lazy Subtour Cut
5:33		 5:33 5:33 1 100 %
07
2026-11-3SAT-07		 Lazy Subtour Cut
2026-11-01 01:20 UTC		 Lazy Subtour Cut
28:18		 28:18 28:18 1 100 %
08
2026-11-3SAT-08		 Lazy Subtour Cut
2026-11-02 01:14 UTC		 Lazy Subtour Cut
23:53:16		 23:53:16 23:53:16 1 100 %

Independent Set

rungFirst solvedQuickest timeAverage timeMedian timeOpened byPercent solved
01
2026-11-IS-01		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:00		 0:00 0:00 1 100 %
02
2026-11-IS-02		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:05		 0:05 0:05 1 100 %
03
2026-11-IS-03		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:01		 0:01 0:01 1 100 %
04
2026-11-IS-04		 Lazy Subtour Cut
2026-11-01 00:47 UTC		 Lazy Subtour Cut
0:27		 0:27 0:27 1 100 %
05
2026-11-IS-05		 Lazy Subtour Cut
2026-11-01 00:48 UTC		 Lazy Subtour Cut
1:19		 1:19 1:19 1 100 %
06
2026-11-IS-06		 Lazy Subtour Cut
2026-11-01 00:58 UTC		 Lazy Subtour Cut
10:01		 10:01 10:01 1 100 %
07
2026-11-IS-07		 Lazy Subtour Cut
2026-11-01 01:58 UTC		 Lazy Subtour Cut
1:00:11		 1:00:11 1:00:11 1 100 %
08
2026-11-IS-08		 — — — — 1 0 %

Clique

rungFirst solvedQuickest timeAverage timeMedian timeOpened byPercent solved
01
2026-11-CLIQUE-01		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:00		 0:00 0:00 1 100 %
02
2026-11-CLIQUE-02		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:01		 0:01 0:01 1 100 %
03
2026-11-CLIQUE-03		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:01		 0:01 0:01 1 100 %
04
2026-11-CLIQUE-04		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:20		 0:20 0:20 1 100 %
05
2026-11-CLIQUE-05		 Lazy Subtour Cut
2026-11-01 00:48 UTC		 Lazy Subtour Cut
1:08		 1:08 1:08 1 100 %
06
2026-11-CLIQUE-06		 Lazy Subtour Cut
2026-11-01 01:04 UTC		 Lazy Subtour Cut
15:58		 15:58 15:58 1 100 %
07
2026-11-CLIQUE-07		 Lazy Subtour Cut
2026-11-01 01:28 UTC		 Lazy Subtour Cut
24:14		 24:14 24:14 1 100 %
08
2026-11-CLIQUE-08		 — — — — 1 0 %

Vertex Cover

rungFirst solvedQuickest timeAverage timeMedian timeOpened byPercent solved
01
2026-11-VC-01		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:00		 0:00 0:00 1 100 %
02
2026-11-VC-02		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:06		 0:06 0:06 1 100 %
03
2026-11-VC-03		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:01		 0:01 0:01 1 100 %
04
2026-11-VC-04		 Lazy Subtour Cut
2026-11-01 00:47 UTC		 Lazy Subtour Cut
0:37		 0:37 0:37 1 100 %
05
2026-11-VC-05		 Lazy Subtour Cut
2026-11-01 00:48 UTC		 Lazy Subtour Cut
1:43		 1:43 1:43 1 100 %
06
2026-11-VC-06		 Lazy Subtour Cut
2026-11-01 00:51 UTC		 Lazy Subtour Cut
2:22		 2:22 2:22 1 100 %
07
2026-11-VC-07		 Lazy Subtour Cut
2026-11-01 02:14 UTC		 Lazy Subtour Cut
1:22:48		 1:22:48 1:22:48 1 100 %
08
2026-11-VC-08		 Lazy Subtour Cut
2026-11-01 02:48 UTC		 Lazy Subtour Cut
34:15		 34:15 34:15 1 100 %

Graph 3-Coloring

rungFirst solvedQuickest timeAverage timeMedian timeOpened byPercent solved
01
2026-11-3COL-01		 Lazy Subtour Cut
2026-11-01 00:47 UTC		 Lazy Subtour Cut
0:01		 0:01 0:01 1 100 %
02
2026-11-3COL-02		 Lazy Subtour Cut
2026-11-01 00:47 UTC		 Lazy Subtour Cut
0:01		 0:01 0:01 1 100 %
03
2026-11-3COL-03		 Lazy Subtour Cut
2026-11-01 00:47 UTC		 Lazy Subtour Cut
0:01		 0:01 0:01 1 100 %
04
2026-11-3COL-04		 Lazy Subtour Cut
2026-11-01 00:56 UTC		 Lazy Subtour Cut
9:19		 9:19 9:19 1 100 %
05
2026-11-3COL-05		 Lazy Subtour Cut
2026-11-01 02:08 UTC		 Lazy Subtour Cut
1:11:22		 1:11:22 1:11:22 1 100 %
06
2026-11-3COL-06		 Lazy Subtour Cut
2026-11-01 02:33 UTC		 Lazy Subtour Cut
25:16		 25:16 25:16 1 100 %
07
2026-11-3COL-07		 Lazy Subtour Cut
2026-11-01 21:52 UTC		 Lazy Subtour Cut
19:19:09		 19:19:09 19:19:09 1 100 %

Hamiltonian Cycle

rungFirst solvedQuickest timeAverage timeMedian timeOpened byPercent solved
01
2026-11-HC-01		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:00		 0:00 0:00 1 100 %
02
2026-11-HC-02		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:06		 0:06 0:06 1 100 %
03
2026-11-HC-03		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:01		 0:01 0:01 1 100 %
04
2026-11-HC-04		 Lazy Subtour Cut
2026-11-01 00:49 UTC		 Lazy Subtour Cut
3:12		 3:12 3:12 1 100 %
05
2026-11-HC-05		 Lazy Subtour Cut
2026-11-01 00:58 UTC		 Lazy Subtour Cut
8:12		 8:12 8:12 1 100 %
06
2026-11-HC-06		 Lazy Subtour Cut
2026-11-01 01:15 UTC		 Lazy Subtour Cut
16:54		 16:54 16:54 1 100 %
07
2026-11-HC-07		 Lazy Subtour Cut
2026-11-01 20:46 UTC		 Lazy Subtour Cut
19:31:08		 19:31:08 19:31:08 1 100 %
08
2026-11-HC-08		 Lazy Subtour Cut
2026-11-02 01:37 UTC		 Lazy Subtour Cut
2:31:39		 2:31:39 2:31:39 1 100 %

Travelling Salesperson (TSP)

rungFirst solvedQuickest timeAverage timeMedian timeOpened byPercent solved
01
2026-11-TSP-01		 Lazy Subtour Cut
2026-11-01 00:47 UTC		 Lazy Subtour Cut
0:03		 0:03 0:03 1 100 %
02
2026-11-TSP-02		 Lazy Subtour Cut
2026-11-01 00:47 UTC		 Lazy Subtour Cut
0:08		 0:08 0:08 1 100 %
03
2026-11-TSP-03		 Lazy Subtour Cut
2026-11-01 00:47 UTC		 Lazy Subtour Cut
0:09		 0:09 0:09 1 100 %
04
2026-11-TSP-04		 — — — — 1 0 %

0-1 Integer Programming

rungFirst solvedQuickest timeAverage timeMedian timeOpened byPercent solved
01
2026-11-ILP-01		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:01		 0:01 0:01 1 100 %
02
2026-11-ILP-02		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:05		 0:05 0:05 1 100 %
03
2026-11-ILP-03		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:00		 0:00 0:00 1 100 %
04
2026-11-ILP-04		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:03		 0:03 0:03 1 100 %
05
2026-11-ILP-05		 Lazy Subtour Cut
2026-11-01 00:47 UTC		 Lazy Subtour Cut
0:21		 0:21 0:21 1 100 %
06
2026-11-ILP-06		 Lazy Subtour Cut
2026-11-01 00:53 UTC		 Lazy Subtour Cut
6:25		 6:25 6:25 1 100 %
07
2026-11-ILP-07		 Lazy Subtour Cut
2026-11-01 22:20 UTC		 Lazy Subtour Cut
21:27:14		 21:27:14 21:27:14 1 100 %

Exact Cover by 3-Sets (X3C)

rungFirst solvedQuickest timeAverage timeMedian timeOpened byPercent solved
01
2026-11-X3C-01		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:00		 0:00 0:00 1 100 %
02
2026-11-X3C-02		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:06		 0:06 0:06 1 100 %
03
2026-11-X3C-03		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:03		 0:03 0:03 1 100 %
04
2026-11-X3C-04		 Lazy Subtour Cut
2026-11-01 00:47 UTC		 Lazy Subtour Cut
0:32		 0:32 0:32 1 100 %
05
2026-11-X3C-05		 Lazy Subtour Cut
2026-11-01 00:50 UTC		 Lazy Subtour Cut
2:56		 2:56 2:56 1 100 %
06
2026-11-X3C-06		 Lazy Subtour Cut
2026-11-01 01:09 UTC		 Lazy Subtour Cut
19:23		 19:23 19:23 1 100 %
07
2026-11-X3C-07		 Lazy Subtour Cut
2026-11-01 21:10 UTC		 Lazy Subtour Cut
20:01:15		 20:01:15 20:01:15 1 100 %
08
2026-11-X3C-08		 Lazy Subtour Cut
2026-11-01 23:05 UTC		 Lazy Subtour Cut
1:53:30		 1:53:30 1:53:30 1 100 %

Problem of the Month (Preview)

rungFirst solvedQuickest timeAverage timeMedian timeOpened byPercent solved
01
2026-12-preview-2026-11-MONTH-01		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:00		 0:00 0:00 1 100 %
02
2026-12-preview-2026-11-MONTH-02		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:00		 0:00 0:00 1 100 %
03
2026-12-preview-2026-11-MONTH-03		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:06		 0:06 0:06 1 100 %
04
2026-12-preview-2026-11-MONTH-04		 Lazy Subtour Cut
2026-11-01 00:46 UTC		 Lazy Subtour Cut
0:04		 0:04 0:04 1 100 %
05
2026-12-preview-2026-11-MONTH-05		 Lazy Subtour Cut
2026-11-01 00:47 UTC		 Lazy Subtour Cut
0:16		 0:16 0:16 1 100 %
06
2026-12-preview-2026-11-MONTH-06		 Lazy Subtour Cut
2026-11-01 00:47 UTC		 Lazy Subtour Cut
0:20		 0:20 0:20 1 100 %
07
2026-12-preview-2026-11-MONTH-07		 Lazy Subtour Cut
2026-11-01 00:48 UTC		 Lazy Subtour Cut
1:31		 1:31 1:31 1 100 %
08
2026-12-preview-2026-11-MONTH-08		 Lazy Subtour Cut
2026-11-01 00:49 UTC		 Lazy Subtour Cut
0:02		 0:02 0:02 1 100 %
09
2026-12-preview-2026-11-MONTH-09		 Lazy Subtour Cut
2026-11-01 00:49 UTC		 Lazy Subtour Cut
0:02		 0:02 0:02 1 100 %
10
2026-12-preview-2026-11-MONTH-10		 Lazy Subtour Cut
2026-11-01 00:49 UTC		 Lazy Subtour Cut
0:18		 0:18 0:18 1 100 %
11
2026-12-preview-2026-11-MONTH-11		 Lazy Subtour Cut
2026-11-01 00:54 UTC		 Lazy Subtour Cut
5:18		 5:18 5:18 1 100 %
12
2026-12-preview-2026-11-MONTH-12		 Lazy Subtour Cut
2026-11-01 01:06 UTC		 Lazy Subtour Cut
13:24		 13:24 13:24 1 100 %