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You need to produce output that is non-deterministic.

In this case, this will be defined to mean that the output will not always be the same result.

Rules:

  • A pseudo-random number generator that always has the same seed does not count.

  • You can rely on the program being run at a different (unknown) time each execution.

  • Your code's process id (if it's not fixed by the interpreter) can be assumed to be non-deterministic.

  • You may rely on web-based randomness.

  • Your code may not take non-empty input. Related meta post.

  • The program is not required to halt, but the output must be displayed.

Leaderboard

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  • 33
    \$\begingroup\$ @mbomb007 In C there are many things that are simply "undefined" behaviour. Any given interpreter is allowed to do whatever it wants in any situation. For all we know, gcc might order you a pizza if you try to overflow a signed integer on a rainy Tuesday, but will make a trout jump out of your screen on all other days. So you wouldn't really ever know if it's actually deterministic or not in any given implementation. \$\endgroup\$ – Martin Ender Nov 30 '16 at 20:44
  • 12
    \$\begingroup\$ @MartinEnder I'm not sure if that matters. We define languages here by their implementation, not by the specification (as languages without an implementation is not allowed) \$\endgroup\$ – Nathan Merrill Nov 30 '16 at 21:00
  • 2
    \$\begingroup\$ @MartinEnder Yeah, I agree with Nathan. \$\endgroup\$ – mbomb007 Nov 30 '16 at 21:01
  • 7
    \$\begingroup\$ Note that undefined behaviour in C often leads to crashes, and crashes on UNIX and Linux lead to core files which contain the process ID inside them. That would seem to comply with the question as currently worded. \$\endgroup\$ – user62131 Nov 30 '16 at 21:23
  • 5
    \$\begingroup\$ Unless I misunderstood, the question did not ask for code that takes advantage of undefined behavior. It asks for code that takes advantage of defined behavior to guarantee non-determinism. \$\endgroup\$ – WGroleau Dec 1 '16 at 3:30

103 Answers 103

1 2 3
4
0
\$\begingroup\$

Batch, 6 4 bytes

time

Needs to be run with <nul which is apparently permissible.

\$\endgroup\$
0
\$\begingroup\$

QBIC, 4 bytes

?_r|

This generates and prints a random number between 0 and 10. QBIC uses the classical RANDOMIZE TIMER at the start of execution to set the RNG.

\$\endgroup\$
0
\$\begingroup\$

Actually, 1 byte

G

Try it online!

Good old rand(). In Python 3, 2500 random bits from the system's cryptographically-secure randomness source (getrandom() for Linux, /dev/urandom for *NIX, or CryptGenRandom for Windows) are used for the seed, falling back on the current UNIX time (as precisely as possible for the given platform - at minimum, 1-second precision) if such a source of randomness is not available.

\$\endgroup\$
0
\$\begingroup\$

Microscript, 2 bytes

r9

Produces a random integer on [0,8]

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0
\$\begingroup\$

Mouse2002, 7 bytes

&RAND !
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0
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Microscript II, 1 byte

R

Produces a random 64-bit float on [0,1).

Another one-byte solution would be C, which produces a new continuation object, whose timestamp (which the reference implementation includes in its string representation) will be nondeterministic.

\$\endgroup\$
0
\$\begingroup\$

HSPAL, 18 bytes

26FFFF
400000
120000

Prints a random 16-bit integer.

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0
\$\begingroup\$

Math++, 5 bytes

$rand

Produces a random 64-bit float

\$\endgroup\$
0
\$\begingroup\$

ASP VBScript, 43 bytes

<%=createobject("scriptlet.typelib").guid%>

Outputs a unique ID like {52076580-3151-4EE7-AAFD-D975CD141EE4} based on current date/time.

\$\endgroup\$
0
\$\begingroup\$

C, 22 bytes

f(){putchar(time(0));}
\$\endgroup\$
  • \$\begingroup\$ OP indicates in the comments that a full program is not needed and a function will suffice. Might I suggest replacing main with f to save 3 bytes? \$\endgroup\$ – Albert Renshaw Apr 11 '17 at 19:48
  • \$\begingroup\$ yes i replace main with f... thank you and a good day \$\endgroup\$ – RosLuP Apr 12 '17 at 5:18
0
\$\begingroup\$

Chip-8, 4 bytes

0xCFFF 'RND vF,FF
0xFF18 'LD ST,vF

This plays a sound for between 0 and 4.25 seconds. The seed always starts at 0, but it updates during the display interrupt which has a tiny chance of happening before the randomizer call, I hope.

\$\endgroup\$
0
\$\begingroup\$

Pyt, 1 byte

ɽ

Returns a random 32-bit integer.

Also 1 byte: ɹ, .

\$\endgroup\$
0
\$\begingroup\$

Gol><>, 3 bytes

x1h

The 'x' is a randomizer for the direction of the pointer, the 1 pushes a 1, and the h outputs and halts.

Try it online!

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  • \$\begingroup\$ You can also do Sxh to print a random float between 0 and 1 \$\endgroup\$ – Jo King Mar 1 '19 at 2:31
  • \$\begingroup\$ @JoKing I didn't think of that, thanks for pointing that out. that works as well. Though I don't think there is a smaller version of this \$\endgroup\$ – KrystosTheOverlord Mar 1 '19 at 2:57
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