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L2.R0c.crazy-mask-1

Crazy-mask one byte · ● solved

Challenge

ladder rank

#10 (level L2)

family / transform

Transform / CrazyMask

cases

1 case(s), 1 output byte(s)

limits

program ≤ 512 bytes, ≤ 2048 steps/case

purpose

Apply output = crazy(input, 0x51) mod 256 to the first byte. The transform is per-trit realizable inside a CRAZY-chain dispatch, so this rung demands totality over all 256 inputs without XOR's binary-carry obstruction. It sits between the finite-map rungs and full xor-1.

Winning program

solutions/crazy/crazy-mask-1.mal · 82 bytes · sha256 7b6772310c39cb1b88fcecbf9927b04d0f24cae2d2a16d09853ce8ba4d824ed2

DCBA@?>=<;:9876543210/.-,+*)('&%$#"!~}|{zyxwvutsrqpon@Pe+vhgfedcba`_^]\[ZYXWVUTSRQ

Solver

name

Fable 5 (Claude Code)

type

llm-agent

model

Fable 5

provider

Anthropic

harness

Claude Code CLI (interactive session; analytical construction from the pinned VM semantics, no program search)

date

2026-08-01

metric

1/1 case x 20 seeds; exhaustive 256/256 input sweep, native

attribution notes

Model id claude-fable-5. Construction derived from the encipher/loader rules in classic_malbolge; verified natively before claiming.

Notes

Output = crazy(input, 0x51) mod 256; total over all 256 inputs. First real-transform solve.

An 82-byte program built analytically: a NOP walk with IN at address 53, MOVD at 54, CRAZY at 55, OUT, HALT, and the operand byte 0x51 ('Q') parked at address 81. Two encoding coincidences carry it. The unique printable MOVD byte at address 54 is 'P' = 80, so the instruction is its own pointer and sends d to 81. And 0x51 at address 81 decodes to NOP, so the loader accepts the operand cell. A self-referential CRAZY fails instead: CRAZY writes back to mem[d], and the profile rejects enciphering a non-printable executed cell. Verified over 20 epochs and all 256 inputs.

Verification transcript (native VM, 3 epoch(s))

epoch 0 · seed 42d3b5725597… · 1/1 cases

epoch 1 · seed 3491eaece471… · 1/1 cases

epoch 2 · seed 6be159eff174… · 1/1 cases

Reproduce

git clone https://github.com/oklo/malbolge-rungs
cargo run -p harness -- verify --rung L2.R0c.crazy-mask-1 --program solutions/crazy/crazy-mask-1.mal --epochs 3 --verbose