Comment by bugfix-66 | Hacker News Reader

Comment by bugfix-66 | Hacker News Reader

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This is a folk algorithm of unknown origin.

All I know is the original author was probably a hacker from Finland and it was originally written in x86 assembly. This is my modernized implementation of his algorithm.

As for solving the BUGFIX-66 puzzles, to fix the bug in the compressor, add

  to = append(to, 0)

on the line after

  loc = len(to)

The original code was not inserting a placeholder for every control byte.

To fix the decompressor, add

  at++

on the line after

  ctrl := int(from[at])

The original code was not stepping past a control byte after loading it.

Doe it literally check for the specific solution?

Writing

    to = append(to, ctrl)

which is functionally equivalent and, in my personal opinion, with clearer intent (ctrl = 0 at that point in the code), returns "incorrect".

In fact, it seems that any placeholder value should work - as it is always overwritten by the final value of ctrl for a given set of bytes at the end; however, the checker rejects this.

Your fix is wrong, so the site rejects it.

Go doesn't do integer type conversions implicitly, to avoid the implicit-type-casting bugs endemic to C. Go (thankfully) doesn't allow an implicit conversion from int to byte. You must do the cast explicitly.

So you would have to say

  to = append(to, byte(ctrl))

and that's correct.

The site builds and executes the code you submit, and any correct solution is accepted.

Thank you!

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