The challenge
Three rails. One very zigzag commute.
One blob of text per attempt; the answer is the slug in the decoded instruction sentence. Written from our solver's report and the saved Single Solve blob.
Reading the prompt: what it said we'd need
| Clue | What it pointed to | What I did about it |
|---|---|---|
| "Three rails" | Rail fence cipher with 3 rails | Nothing new: the chain has decoded rail fence since the Day 15 pre-build |
| "zigzag" | The rail fence's write pattern (down and up the rails) | Same |
What was in the files
The Single Solve blob was 109 bytes of readable letters in the wrong order, with spaces and punctuation kept: the letter mix of a normal English sentence, scrambled. That's the sign of a transposition, not a substitution. The timed sets used the same template; Mastery blobs carry one line per day, with today's layer on the last line.
The modes
Single Solve CORRECT 09:00:15 flag 7dfffd9f…e666 solve 7 ms, submit +1.39 s
Time Trial CORRECT 09:00:22 flag bbd162f2…83b8 solve 13 ms, submit +1.78 s (unranked: 0 unique attempts)
Mastery CORRECT 09:00:30 flag 303c8581…5870 solve 249 ms, submit +1.81 s
Time to solve
All three modes were solved by 09:00:30 ET, 30 s after release, each on the first submit and with no hand work; the Time Trial was unranked.
Takeaways
- Breadth pays off: a decoder pre-built three days early answered today's layer with no change, so Warmups finished 30 s after release.
- The Time Trial was a single-variant route (
unique_attempts_remaining: 0, unranked). Because the solver always proves the Single Solve first, the one attempt went through.