Choose a language and write a program in the language that:

  • Take a valid program of the language as input,
  • Output a string(bytearray, etc.). It needn't be a valid program.
  • Only finite valid inputs result in longer/same-length(in bytes) output.
  • Different valid input, even if behave same, lead to different output.

Let length of your code as \$L\$ and number of inputs with longer/equal-length output as \$n\$. To win, you should be lowest on at least one of:

  • \$L\$,
  • \$N\$,
  • \$L+N\$,
  • \$L+\log_2(N+1)\$.


  • 1
    \$\begingroup\$ Please make the objective and rules of the challenge clearer. \$\endgroup\$
    – Binary198
    Commented Jan 19, 2022 at 16:56
  • 1
    \$\begingroup\$ @Binary198 Please make your request clearer :) \$\endgroup\$
    – l4m2
    Commented Jan 19, 2022 at 17:01
  • \$\begingroup\$ Well, what is the program intended to do exactly, and how does the scoring system work? \$\endgroup\$
    – Binary198
    Commented Jan 19, 2022 at 17:04
  • \$\begingroup\$ @Binary198 To compress all programs but finite ones. Some users would make four questions for four scoring way but it likely make a mess \$\endgroup\$
    – l4m2
    Commented Jan 19, 2022 at 17:07
  • \$\begingroup\$ So, you need to take a program as input and output a unique string that will be longer than or equal to in length than the input? Still, the scoring system is weird. What is \$N\$, and why are there multiple scoring ways? I would usually just go with one. \$\endgroup\$
    – Binary198
    Commented Jan 19, 2022 at 17:10

1 Answer 1


Python 3.8 (pre-release), \$L=79\$, \$N\approx255^{1500}\$

-3 bytes thanks to @Jonathan Allan

f=lambda b,s=0,l=0:b and f(b[1:],255*s+b[0],l+1)or s.to_bytes(l-(l>1500),"big")

Try it online!

Python source code can't contain null bytes. This converts the input (bytestring) to base 255 and then back to bytes. After 1500 removes a redundant byte.

  • \$\begingroup\$ Do you save one byte iff length>1500? \$\endgroup\$
    – l4m2
    Commented Jan 19, 2022 at 17:21
  • \$\begingroup\$ @l4m2 Yes, exactly \$\endgroup\$
    – AnttiP
    Commented Jan 19, 2022 at 17:22
  • \$\begingroup\$ You don't need the f= (I guess you were going to go with a recursive function which would need it, and left it in). \$\endgroup\$ Commented Jan 19, 2022 at 19:02
  • 1
    \$\begingroup\$ Using recursion (which I think we may assume to have no limit set for code-golf purposes), you could do f=lambda b,s=0,l=0:b and f(b[1:],255*s+b[0],l+(l!=1500))or s.to_bytes(l,"big") for \$L=78\$ TIO \$\endgroup\$ Commented Jan 19, 2022 at 19:09
  • \$\begingroup\$ Hmm, maybe not - I don't understand this error \$\endgroup\$ Commented Jan 19, 2022 at 19:26

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