What's the odd one out?

Question

You are to write a program which outputs a single positive integer \$n\$. The integer may have leading zeros and whitespace, and/or trailing whitespace.

Then, choose a positive integer \$m > 1\$. When the program is repeated exactly \$m\$ times, it should output \$m \times n\$ (and only \$m\times n\$). When repeated any number of times other than \$m\$, it should output \$n\$ (and only \$n\$).

You may choose the value of \$m\$, so long as it is a positive integer greater than 1.

In this context, "repeated \$m\$ times" means that the whole program is repeated \$m\$ times, rather than each character. For example, repeating abcde \$4\$ times yields abcdeabcdeabcdeabcde.

This is code-golf so the shortest code (not repeated \$m\$ times) in bytes wins.

For example, if your program is print 5 which outputs 5, and you choose \$m = 3\$, then:

print 5 should output 5
print 5print 5 should output 5
print 5print 5print 5 should output 15
print 5print 5print 5print 5 should output 5
print 5print 5print 5print 5print 5 should output 5
etc.

Huh, I accidentally chose the same n and m as the example. Spooky! — Neil, Mar 9, 2021 at 21:17
@Kaddath If n is zero, then the program always outputs 0, no matter \$m\$, so no — caird coinheringaahin g, Mar 10, 2021 at 13:10
@OlivierGrégoire Yes (and I think a lot of answers already do so), so long as it still "works" as specified when repeated — caird coinheringaahin g, Mar 11, 2021 at 15:45

Robin Ryder · Accepted Answer · 2021-03-10 15:30:43Z

9

R, 16 bytes

T=a=1+!T;T=T-1;a

Try it online!

Works with \$n=1\$ and \$m=2\$.

Previous version:

R, 24 23 21 19 bytes

-4 bytes thanks to Dominic van Essen

T=a=1+0^T^2;T=T-1;a

Try it online!

Works with \$n=1\$ and \$m=2\$. This uses the fact that

\$0^k = \begin{cases} 1 & \text{ if } k=0\\0& \text { otherwise.}\end{cases}\$

Therefore, when the code is repeated \$k\$ times, we output \$1+0^{(2-k)^2}\$, which is worth \$2\$ when \$k=2\$, and \$1\$ otherwise.

edited Mar 10, 2021 at 15:30

answered Mar 9, 2021 at 19:45

Robin Ryder

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\$\begingroup\$ 21 bytes \$\endgroup\$
– Dominic van Essen
Mar 10, 2021 at 6:52
\$\begingroup\$ @DominicvanEssen Neat, thanks! \$\endgroup\$
– Robin Ryder
Mar 10, 2021 at 7:15
\$\begingroup\$ 19 bytes \$\endgroup\$
– Dominic van Essen
Mar 10, 2021 at 15:12
\$\begingroup\$ @DominicvanEssen Thanks again! \$\endgroup\$
– Robin Ryder
Mar 10, 2021 at 15:25

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Dominic van Essen · Accepted Answer · 2021-03-10 08:02:10Z

7

R, 27 20 18 bytes

Edit: -2 bytes thanks to Robin Ryder, and -2 bytes thanks to pajonk

b=a=3^!(F=F+1)-3;a

Try it online!

n=1, m=3 (or trivially for any m up to 9 for same bytes...)

edited Mar 10, 2021 at 8:02

answered Mar 9, 2021 at 18:23

Dominic van Essen

34.6k2 gold badges18 silver badges54 bronze badges

1

\$\begingroup\$ 25 bytes \$\endgroup\$
– Robin Ryder
Mar 10, 2021 at 5:43
\$\begingroup\$ @RobinRyder - Thanks! That inspired me to get rid of 5 more, too...! \$\endgroup\$
– Dominic van Essen
Mar 10, 2021 at 6:25
\$\begingroup\$ Shouldn't this work for second approach? Try it online! \$\endgroup\$
– pajonk
Mar 10, 2021 at 7:27
1

\$\begingroup\$ @pajonk - Thanks! That's amazing - I never would have thought that the operator precedence could allow that! It looks so wrong, but works! Cool. \$\endgroup\$
– Dominic van Essen
Mar 10, 2021 at 8:04

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Digital Trauma · Accepted Answer · 2021-03-09 18:32:36Z

6

Bash, 26

n=3, m=2

trap echo\ $[++a-2?3:6] 0

Try it online!

Try it online!Try it online!

Try it online!Try it online!Try it online!

answered Mar 9, 2021 at 18:32

Digital Trauma

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Manish Kundu · Accepted Answer · 2021-03-10 05:29:58Z

6

Python 3, 77 50 46 43 39 37 bytes

input(1+(len([*open(__file__)])==2))

Try it online!

Simply counts the number of lines of the code and returns 2 if it is 2 and one otherwise. The x is not defined and causes a runtime error immediately after and ends the program.

$$n=1, m=2$$

Thanks to ChartZ Belatedly for -27 bytes, FryAmTheEggman for -3 bytes, pxeger for -4 bytes and dingledooper for -2 bytes.

edited Mar 10, 2021 at 5:29

answered Mar 9, 2021 at 18:24

Manish Kundu

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\$\begingroup\$ 50 bytes using the same trick \$\endgroup\$
– caird coinheringaahin g ♦
Mar 9, 2021 at 18:26
\$\begingroup\$ Changing from indexing to computing a power saves enough to get 47 bytes. \$\endgroup\$
– FryAmTheEggman
Mar 9, 2021 at 19:04
1

\$\begingroup\$ 36 by outputting via exit code and counting lines: Try it online! \$\endgroup\$
– pxeger
Mar 9, 2021 at 20:53
\$\begingroup\$ @pxeger the counting lines is smart, but I believe by output the OP means standard output only so using exit code for that is probably not allowed. \$\endgroup\$
– Manish Kundu
Mar 10, 2021 at 5:05
1

\$\begingroup\$ You can use input() to get 37 bytes. \$\endgroup\$
– dingledooper
Mar 10, 2021 at 5:22

| Show 1 more comment

recursive · Accepted Answer · 2021-03-09 18:53:05Z

5

Stax, 5 bytes

|d1=^

Run and debug it

Run and debug itRun and debug it

Run and debug itRun and debug itRun and debug it

This works for m = 2, n = 1.

answered Mar 9, 2021 at 18:53

recursive

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Zaelin Goodman · Accepted Answer · 2021-03-09 19:29:41Z

5

PowerShell, 22 bytes, \$n=1\$, \$m=2\$

+!$x+!(++$x-2)-!($x-3)

Try it online!

Try it online!Try it online!

Try it online!Try it online!Try it online!

PowerShell, 39 bytes, \$n=1\$, \$m=2\$

1+((gc $PSCommandPath).Count-eq2);exit

Try it online!

PowerShell 7, 39 bytes, \$n=1\$, \$m=2\$

(gc $PSCommandPath).Count-eq2?2:1;exit

edited Mar 9, 2021 at 19:29

answered Mar 9, 2021 at 18:21

Zaelin Goodman

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Neil · Accepted Answer · 2021-03-09 21:16:02Z

5

Charcoal, 11 bytes

⎚⊞υω×1⁼³Ｌυ5

\$n=5\$, \$m=3\$. Try it online! Try it online!Try it online! Try it online!Try it online!Try it online! Try it online!Try it online!Try it online!Try it online! Explanation:

⎚

Clear the canvas of output from the previous copy.

⊞υω

Track the number of copies.

×1⁼³Ｌυ

If that's 3 then print a 1.

Always print a 5.

answered Mar 9, 2021 at 21:16

Neil

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pxeger · Accepted Answer · 2021-03-10 08:31:59Z

4

Zsh `-F`, 21 bytes, \$n=1\$, \$m=4\$

bye `wc -l<$0`-5?1:4

Try it online!

Try it online!Try it online!Try it online!Try it online!

Note the trailing newline. Outputs via exit code.

edited Mar 10, 2021 at 8:31

answered Mar 9, 2021 at 20:29

pxeger

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Unmitigated · Accepted Answer · 2021-03-10 14:05:57Z

4

JavaScript, 65 60 57 46 45 bytes, \$n = 1, m = 5\$

var i=-~i;setTimeout(_=>i=i&&alert(i^5?1:5));

Saved 3 bytes thanks to Arnauld.

Saved 11 bytes thanks to user81655

Saved 1 byte thanks to Neil

By itself:

var i=-~i;setTimeout(_=>i=i&&alert(i^5?1:5));

Repeated 5 times:

var i=-~i;setTimeout(_=>i=i&&alert(i^5?1:5));var i=-~i;setTimeout(_=>i=i&&alert(i^5?1:5));var i=-~i;setTimeout(_=>i=i&&alert(i^5?1:5));var i=-~i;setTimeout(_=>i=i&&alert(i^5?1:5));var i=-~i;setTimeout(_=>i=i&&alert(i^5?1:5));

edited Mar 10, 2021 at 14:05

answered Mar 9, 2021 at 18:55

Unmitigated

2,7491 gold badge4 silver badges14 bronze badges

1

\$\begingroup\$ this.i=-~this.i should save 3 bytes. \$\endgroup\$
– Arnauld
Mar 9, 2021 at 22:10
1

\$\begingroup\$ You should also be able to remove the this. at the start \$\endgroup\$
– user81655
Mar 10, 2021 at 1:17
1

\$\begingroup\$ b&&(b=alert(i^5?1:5)) can become b=b&&alert(i^5?1:5) \$\endgroup\$
– user81655
Mar 10, 2021 at 1:19
1

\$\begingroup\$ Also you could replace b with i so you don't have to declare ,b=1 \$\endgroup\$
– user81655
Mar 10, 2021 at 1:23
1

\$\begingroup\$ var i=-~i; is an alternative way to save a byte. \$\endgroup\$
– Neil
Mar 10, 2021 at 11:45

| Show 2 more comments

Silvio Mayolo · Accepted Answer · 2021-03-25 23:58:33Z

Factor, 172 bytes, n = 2, m = 4

Let's see some love for the language of the month.

 USING: prettyprint namespaces init math io kernel ; IN: main 0 1 set-global
1 get-global 1 + 1 set-global [ 1 get-global 4 = [ 8 ] [ 2 ] if . flush ] 2 add-shutdown-hook !

(The leading space before USING: is significant, and so is the lack of newline at the end)

We store a simple counter in a global variable (global variables in Factor are, by convention, symbols, but there's no actual requirement, so our global variable is named the integer 1). Then the part of our code that "repeats" simply increments this global. We register a shutdown hook that does the final checks for us. The fact that we register the hook several times is irrelevant, because we give it the same name each time (this name, incidentally, is the integer 2; once again, Factor is happy to accept a very loose definition of "name").

Try it online!

Try it online!Try it online!

Try it online!Try it online!Try it online!

Try it online!Try it online!Try it online!Try it online!

Unmitigated · Accepted Answer · 2021-03-11 21:31:00Z

3

Java 6, 120 77 bytes, \$n=1, m=2\$

enum A{A;{System.out.print(new java.io.File("A.java").length()==154?2:1);}}//

Saved 43 bytes thanks to Olivier Grégoire.

edited Mar 11, 2021 at 21:31

answered Mar 10, 2021 at 16:06

Unmitigated

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1

\$\begingroup\$ I think usually if you assume a file name you need to include it in your byte score (also you can use a name of a I think) \$\endgroup\$
– Command Master
Mar 10, 2021 at 16:22
\$\begingroup\$ @CommandMaster Since the interface is named Main, it cannot be run unless the file name is Main.java. \$\endgroup\$
– Unmitigated
Mar 10, 2021 at 17:30
\$\begingroup\$ @iota I just tried that and it seems to work. \$\endgroup\$
– user
Mar 10, 2021 at 17:33
1

\$\begingroup\$ 1. Your program can be shortened for Java versions 5 & 6: codegolf.stackexchange.com/a/140181/16236 2. You can get rid of the public as Java allows running it if you call java Main.java (yes, without compiling). 3. You can name the class A. All in all, you can reduce to 92 bytes: enum A{A;{System.out.print(new java.io.File("A.java").length()==184?2:1);System.exit(0);}}// You don't need to have it running on TIO to have a valid submission. \$\endgroup\$
– Olivier Grégoire
Mar 11, 2021 at 15:44
1

\$\begingroup\$ Also, usually, Codegolf rules allow you to write to stderr after you've output the correct value, so this 77 bytes solution would work: enum A{A;{System.out.print(new java.io.File("A.java").length()==154?2:1);}}//. Then, running java A.java on Java 5 or 6 will yield the correct output. \$\endgroup\$
– Olivier Grégoire
Mar 11, 2021 at 15:47

| Show 9 more comments

Command Master · Accepted Answer · 2021-03-25 18:50:10Z

3

05AB1E, 6 5 4 bytes, \$ n=1, m=2 \$

-1 thanks to @Kevin Cruijssen

.gΘ>

Try it online!

edited Mar 25, 2021 at 18:50

answered Mar 10, 2021 at 15:49

Command Master

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\$\begingroup\$ Can't your second solution be 4 bytes by replacing the 1+ with >? \$\endgroup\$
– Kevin Cruijssen
Mar 25, 2021 at 15:45
\$\begingroup\$ It can, I'm not sure how I didn't notice that. Thanks! \$\endgroup\$
– Command Master
Mar 25, 2021 at 18:49

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Etheryte · Accepted Answer · 2021-03-10 01:36:55Z

2

Japt, 8 6 bytes, \$n=1\$, \$m=2\$

Works because Javascript numbers don't overflow from positive to negative.
Essentially J is incremented to infinity, 2 is output only on the case of two repetitions.

J°?1:2 // J is a builtin variable that equals -1 at first.
J°     // If J++ is truthy (-1, 1, 2, etc)
  ?1:2 // output 1, otherwise 2.

Try it here.

edited Mar 10, 2021 at 1:36

answered Mar 9, 2021 at 21:04

Etheryte

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user81655 · Accepted Answer · 2021-03-10 01:37:51Z

2

JavaScript (V8), 40 bytes

0;i=-~this.i,{get x(){print(i-3?1:3)}}.x

Try it online!

Uses the same trick as my solution the other day. The core idea is putting the print() behind a getter function. If the .x property is accessed it will print the result. This is placed at the end of the generated code so that it accesses .x on the last iteration but when concatenated it becomes .x0 (does not access .x).

answered Mar 10, 2021 at 1:37

user81655

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tsh · Accepted Answer · 2021-03-10 02:59:41Z

2

JavaScript (Node.js), 26 bytes, \$n=1\$, \$m=2\$

(x=>x?y=>y?g=z=>z?g:1:2:1)

Try it online!

Is this valid? I'm not quite sure...

JavaScript (SpiderMonkey), 28 bytes, \$n=1\$, \$m=2\$

f=x=>((f+'').length==54)+1//

Try it online!

Another similar answer (requires Firefox 86-)

edited Mar 10, 2021 at 2:59

answered Mar 10, 2021 at 2:43

tsh

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MarcMush · Accepted Answer · 2021-03-10 09:30:23Z

2

Julia, 20 bytes, \$n=1\$, \$m=2\$

a=b=1;a+=1;b+=a==3;b

Try it online!

answered Mar 10, 2021 at 9:30

MarcMush

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Kaddath · Accepted Answer · 2021-03-10 11:03:58Z

PHP, 38 34 bytes \$n=1\$ \$m=2\$

<?=count(file(__FILE__))!=3?:2;
//

Try it online!

This hacky solution relies on getting the current code's first line and testing the length is 76 (38 * 2). Works as a standalone but needs the // to comment any repetitions of the program so that only one output is displayed. Also in ternary conditions a?b:c, if b is missing, the value of a is used, and in PHP true is displayed as 1.

EDIT: saved 4 bytes by counting the lines of code instead of length of the first line. Notice the newline before the comment

Mthd · Accepted Answer · 2021-04-09 13:41:38Z

Brainfuck, ²⁶⁸264 characters / ¹⁰¹99 bytes, n=1, m=2

    ++>+ Init
    [->+>+<<]>>[-<<+>>]< Copy second into third
    [-<<->>]<< Check if equal
        [ If not equal
            [-] Reset first
            +++++++++++++++++++++++++++++++++++++++++++++++++
            .
            ------------------------------------------------- Output 1
            >>>-<<< Set a flag saying that this cycle was passed
        ]
        >>>+ Change the flag
        [ If the flag is nonzero (meaning the previous cycle was not passed)
            [-] Reset the flag
            ++++++++++++++++++++++++++++++++++++++++++++++++++
            .
            -------------------------------------------------- Output 2
        ]
    <[-]<<[-] Reset first and third

Try it online!

This can take a while to run, so set the delay to minimum if you want to test it.

Definitely not a good golfing language, but it was interesting to write just for the sake of it.

(This challenge is impossible to complete in BF as it's stated because repeated code will always produce a multiple-char output, so in this solution the answer is the last output char)

Edit: I'm completely brain dead and forgot this is code golf, so I wrote the last lines in a really weird way. Corrected, saved 4 chars.

Can you assume an env supporting \r or \b to erase last output? — l4m2, Apr 9, 2021 at 11:48

Aaroneous Miller · Accepted Answer · 2021-04-09 15:26:29Z

2

Grok, 31 bytes, n=1, m=2

`  j
ljq
11z
+=1
 {k
j2`h
`lzq

Note the single trailing newline. Program was multiplied with cat odd1out >> odd2out. At first I thought I would have to rework my solution because of how programs need to be multiplied, but then I realized I could just turn it on its side.

answered Apr 9, 2021 at 15:26

Aaroneous Miller

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Stack Exchange Network

What's the odd one out?

19 Answers 19

R, 16 bytes

R, 24 23 21 19 bytes

R, 27 20 18 bytes

Bash, 26

Python 3, 77 50 46 43 39 37 bytes

Stax, 5 bytes

PowerShell, 22 bytes, \$n=1\$, \$m=2\$

PowerShell, 39 bytes, \$n=1\$, \$m=2\$

PowerShell 7, 39 bytes, \$n=1\$, \$m=2\$

Charcoal, 11 bytes

Zsh `-F`, 21 bytes, \$n=1\$, \$m=4\$

JavaScript, 65 60 57 46 45 bytes, \$n = 1, m = 5\$

Factor, 172 bytes, n = 2, m = 4

Java 6, 120 77 bytes, \$n=1, m=2\$

05AB1E, 6 5 4 bytes, \$ n=1, m=2 \$

Japt, 8 6 bytes, \$n=1\$, \$m=2\$

JavaScript (V8), 40 bytes

JavaScript (Node.js), 26 bytes, \$n=1\$, \$m=2\$

JavaScript (SpiderMonkey), 28 bytes, \$n=1\$, \$m=2\$

Julia, 20 bytes, \$n=1\$, \$m=2\$

PHP, 38 34 bytes \$n=1\$ \$m=2\$

Brainfuck, ²⁶⁸264 characters / ¹⁰¹99 bytes, n=1, m=2

Grok, 31 bytes, n=1, m=2

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code-golf
source-layout
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What's the odd one out?

19 Answers 19

R, 16 bytes

R, 24 23 21 19 bytes

R, 27 20 18 bytes

Bash, 26

Python 3, 77 50 46 43 39 37 bytes

Stax, 5 bytes

PowerShell, 22 bytes, \$n=1\$, \$m=2\$

PowerShell, 39 bytes, \$n=1\$, \$m=2\$

PowerShell 7, 39 bytes, \$n=1\$, \$m=2\$

Charcoal, 11 bytes

Zsh -F, 21 bytes, \$n=1\$, \$m=4\$

JavaScript, 65 60 57 46 45 bytes, \$n = 1, m = 5\$

Factor, 172 bytes, n = 2, m = 4

Java 6, 120 77 bytes, \$n=1, m=2\$

05AB1E, 6 5 4 bytes, \$ n=1, m=2 \$

Japt, 8 6 bytes, \$n=1\$, \$m=2\$

JavaScript (V8), 40 bytes

JavaScript (Node.js), 26 bytes, \$n=1\$, \$m=2\$

JavaScript (SpiderMonkey), 28 bytes, \$n=1\$, \$m=2\$

Julia, 20 bytes, \$n=1\$, \$m=2\$

PHP, 38 34 bytes \$n=1\$ \$m=2\$

Brainfuck, 268264 characters / 10199 bytes, n=1, m=2

Grok, 31 bytes, n=1, m=2

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Zsh `-F`, 21 bytes, \$n=1\$, \$m=4\$

Brainfuck, ²⁶⁸264 characters / ¹⁰¹99 bytes, n=1, m=2

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code-golf
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