TIS-100 Bench: Sequence Reverser

42656 Easy Sequence algorithms Memory & interpreters Built-in puzzle · TIS-100 Bench report →

Reverse zero-terminated sequences using the available stack memory. Reading, storing, and draining must agree on sequence boundaries.

In TIS-100 Bench, 16 LLMs each had one attempt at this TIS-100 puzzle, with 10 minutes to find a working program and keep improving it, without seeing the community leaderboard. 15 of 16 models solved it. No model found a new Pareto-frontier point beyond the community leaderboard.

15 / 16models solved it
240best LLM cycles (184 community)
0new frontier points

Records

ScoreCommunity bestBest LLMModel
Cycles184240Gemini 4 Argon · +30%
Nodes33DeepSeek V4.1 Flash Ties record
Instructions88GPT-6 Astra Ties record

Community records from the community leaderboard when we froze it. A record counts only after fresh-game replay and 100,000 passing random tests.

Pareto frontier

Pareto explorer

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Every model

ModelSolvedBest cyclesBest nodesBest instructionsNew frontier points
01Gemini 4 ArgonYes24038—
02GPT-6 AstraYes24238—
03Opus 5.5Yes24838—
04Sonnet 5.5Yes24938—
05GPT-6.1 SolYes25639—
06Fable 5.1Yes275411—
07Kimi K3.1 ProYes319411—
08Muse Spark 1.3Yes319411—
09DeepSeek V4.1 FlashYes342310—
10Grok 4.7Yes343310—
11Muse Wonder 1.0Yes347415—
12Haiku 5.5Yes350411—
13Gemini 3.8 FlashYes394414—
14GPT-6 LunaYes408415—
15GLM-5.3Yes428417—
16MiMo-V2.6-ProNo————

Best scores can come from different programs. New frontier points are not matched or beaten on all three scores by any community program.

Best model programs

These programs are in TIS-100 save format and released under the MIT License. All of this puzzle’s model programs are on GitHub and Hugging Face.

Gemini 4 Argon Fewest cycles

240 cycles · 4 nodes · 25 instructions42656.240-4-25.txt on GitHub

Gemini 4 Argon program running on 42656 in TIS-100
Node 1
O: MOV ACC, RIGHT
   MOV UP, ACC
   JNZ O
   MOV ACC, DOWN
E: MOV UP, ACC
   MOV ACC, DOWN
   JNZ E
   MOV DOWN, ACC
Node 4
   MOV UP, RIGHT
I: MOV ACC, DOWN
   MOV UP, ACC
   JNZ I
   MOV RIGHT, UP
O: MOV DOWN, ACC
   MOV ACC, RIGHT
   JNZ O
Node 5
   MOV LEFT, NIL
O: MOV UP, ACC
   MOV ACC, DOWN
   JNZ O
   MOV ACC, LEFT
E: MOV LEFT, ACC
   MOV ACC, DOWN
   JNZ E
Node 7
MOV UP, DOWN

GPT-6 Astra Fewest nodes

284 cycles · 3 nodes · 19 instructions42656.284-3-19.txt on GitHub

GPT-6 Astra program running on 42656 in TIS-100
Node 1
S: MOV UP ACC
JEZ Z
NEG
A: MOV ACC RIGHT
MOV UP ACC
JNZ A
B: MOV RIGHT ACC
MOV ACC DOWN
JGZ B
JMP S
Z: MOV 0 DOWN
Node 4
MOV UP ACC
JGZ P
NEG
JEZ P
MOV ACC DOWN
MOV 0 ACC
P: MOV ACC DOWN
Node 7
MOV LEFT DOWN

GPT-6 Astra Fewest instructions

314 cycles · 3 nodes · 8 instructions42656.314-3-8.txt on GitHub

GPT-6 Astra program running on 42656 in TIS-100
Node 1
A: MOV ACC RIGHT
MOV UP ACC
JNZ A
B: MOV RIGHT ACC
MOV ACC DOWN
JNZ B
Node 4
MOV UP DOWN
Node 7
MOV LEFT DOWN