Given two integers, output the two integers, and then the range between them (excluding both).

The order of the range must be the same as the input.

Examples:

 Input        Output
 0,  5   ->   [0, 5, 1, 2, 3, 4]
-3,  8   ->   [-3, 8, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7]
 4,  4   ->   [4, 4]
 4,  5   ->   [4, 5]
 8,  2   ->   [8, 2, 7, 6, 5, 4, 3]
-2, -7   ->   [-2, -7, -3, -4, -5, -6]
  • I guess we can't take the inputs in pre-ordered order? – Kevin Cruijssen Nov 8 at 9:55
  • @KevinCruijssen, no, the output order depends on the input order – TFeld Nov 8 at 9:58
  • @StewieGriffin, the output order has to be the same as the input – TFeld Nov 8 at 9:58
  • Is this output format acceptable? Note the newline – Luis Mendo Nov 8 at 10:48
  • 2
    @KevinCruijssen Any reasonable I/O is acceptable. – TFeld Nov 8 at 13:08

51 Answers 51

R, 39 33 30 bytes

c(a<-scan(),setdiff(a:a[2],a))

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Thanks for saved bytes to user2390246 and J.Doe.

  • You could save a few bytes by taking the input as a vector rather than as two separate integers. – user2390246 Nov 8 at 11:47
  • Yeah, that's reasonable, and it actually then becomes even shorter as a full program rather than function. – Kirill L. Nov 8 at 12:04
  • You can abuse the fact the : operator uses the first element of both args for 30 bytes – J.Doe Nov 8 at 12:20

05AB1E, 4 bytes

Ÿ¦¨«

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Explanation

    Ÿ      # inclusive range [a ... b]
     ¦¨    # remove the first and last element
       «   # append to input

Python 3, 52 48 47 42 bytes

lambda a,b:[a,b,*range(a,b,(a<b)*2-1)[1:]]

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Combined former implementations.

New contributor
cobaltp is a new contributor to this site. Take care in asking for clarification, commenting, and answering. Check out our Code of Conduct.
  • 2
    You can remove the space at or-1 to save a byte. – Kevin Cruijssen Nov 8 at 9:56

Python 2 (Cython), 36 35 bytes

lambda x:x+range(*x,-cmp(*x)|1)[1:]

Thanks to @nwellnhof for golfing off 1 byte!

Try it online!


Python 2, 37 bytes

lambda x:x+range(*x+[-cmp(*x)|1])[1:]

Thanks to @JonasAusevicius for the port to CPython!

Try it online!

  • 2
    This can be applied to standard Python 2 at 37 bytes, making it the shortest answer yet: lambda x:x+range(*x+[-cmp(*x)|1])[1:]. Nice solution – Jonas Ausevicius Nov 8 at 14:17

Perl 6, 26 22 bytes

{|@_,|[...^](@_).skip}

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Explanation

{                    }
 |@_,   # Slip args a,b into result
      [...^](@_)  # Reduce args a,b with ...^ operator, same as a...^b
                .skip  # Skip first element
     |  # Slip into result

Python 2, 40 bytes

lambda x,y:[x,y]+range(x,y,-(y<x)|1)[1:]

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  • Really like -(y<x)|1. very cool but I can't work out why it works! Any chance you can explain it? – ElPedro Nov 8 at 19:06
  • 2
    @ElPedro Basically, y<x checks if y is strictly less than x, and returns True if it is, False otherwise. After that, unary - is applied to it, which converts True to -1 and False to 0. The last step is to bitwise OR this number with 1. This obviously leaves 1 (0b1) unaffected, and also leaves -1 (-0b1) unaffected (the sign bit of -1 is set, so it's kept as such). However, it does convert 0 to 1, so that range doesn't complain about me using a step of 0. – Erik the Outgolfer Nov 8 at 19:32
  • That is seriously cool and very clever. If I could upvote twice I would. Many thanks for the explanation. – ElPedro Nov 8 at 20:27

Python 3, 64 62 51 bytes

lambda a,b:[a,b]+[*range(a+1,b)]+[*range(a-1,b,-1)]

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Python 2, 58 45 bytes

lambda a,b:[a,b]+range(a+1,b)+range(a-1,b,-1)

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New contributor
Jonas Ausevicius is a new contributor to this site. Take care in asking for clarification, commenting, and answering. Check out our Code of Conduct.
  • 2
    Because an empty list is falsey, you can remove the a<=b and from both answers – TFeld Nov 8 at 10:03
  • You could also use + instead of or – TFeld Nov 8 at 10:13
  • @TFeld thank you – Jonas Ausevicius Nov 8 at 10:24

Python 2, 47 41 bytes

lambda a,b:[a,b]+range(a,b,(a<b)*2-1)[1:]

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Here's mine, now that a lot of other Python answers have been posted

-6 bytes, thanks to G B

  • Taking advantage of the empty range when it's invalid is a smart way to deal with forward or backwards lists. I could see that being very useful and is a nice trick to know exists. – akozi Nov 8 at 12:21
  • 2
    41 bytes using a single range: range(a,b,(a<b)*2-1) – G B Nov 8 at 12:35

Japt, 8 bytes

cUr!õ kU

Try it here

             :Implicit input of array U
c            :Concatenate
 Ur          :  Reduce U by
   !õ        :   Inclusive range
      kU     :  Remove all elements in original U

JavaScript (ES6), 51 bytes

Takes input as (a)(b).

a=>g=(b,c=b)=>(b+=b<a|-(b>a))-a?[...g(b,c),b]:[a,c]

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Commented

a =>                // main function, taking a
  g = (             // g = recursive function
    b,              //     taking b
    c = b           // we save a backup of the original value of b into c
  ) =>              //
    (b +=           // add to b:
      b < a |       //   +1 if b is less than a
      -(b > a)      //   -1 if b is greater than a
    )               //   (or 0 if b = a)
    - a ?           // if the updated value of b is not equal to a:
      [             //   generate a new array:
        ...g(b, c), //     prepend all values generated by a recursive call
        b           //     append the current value of b
      ]             //
    :               // else:
      [a, c]        //   stop recursion and return the first 2 values: a and c

Java 10, 109 108 104 102 93 62 bytes

Using a space-delimited String:

b->a->{var r=a+" "+b;for(;a<b?++a<b:--a>b;)r+=" "+a;return r;}

Try it online.

Using a List:

b->a->{var r=new java.util.Stack();for(r.add(a),r.add(b);a<b?++a<b:--a>b;)r.add(a);return r;}

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(a<b?++a<b:--a>b can be ++a<b||(a-=2)>b for the same byte-count: Try it online for the String or Try it online for the List.)


Old (109 108 104 102 101 bytes) answer using an array:

a->b->{int s=a<b?1:-1,i=a!=b?(b-a)*s+1:2,r[]=new int[i];for(r[0]=a,r[1]=b;i>2;)r[--i]=b-=s;return r;}

-7 bytes thanks to @nwellnhof.

Try it online.

Explanation:

a->b->{                // Method with 2 int parameters & int-array return-type
  int s=               //  Step integer, starting at:
        a<b?1          //   1 if the first input is smaller than the second
        :-1;           //   -1 otherwise
      i=               //  Array-index integer, starting at:
        a!=b?          //   If the inputs aren't equal:
         (b-a)*s+1     //    Set it to the absolute difference + 1
        :              //   Else:
         2,            //    Set it to 2
      r[]=new int[i];  //  Result-array of that size
  for(r[0]=a,          //  Fill the first value with the first input
      r[1]=b;          //  And the second value with the second input
      i>2;)            //  Loop `i` downwards in the range [`i`,2):
    r[--i]=            //   Decrease `i` by 1 first with `--i`
                       //   Set the `i`'th array-value to:
           b-=s;       //    If the step integer is 1: decrease `b` by 1
                       //    If the step integer is -1: increase `b` by 1
                       //    And set the array-value to this modified `b`
  return r;}           //  Return the result-array
  • Isn't there anything in Java's standard library for making ranges of integers? Or it is just too verbose to use? – Οurous Nov 8 at 11:17
  • @Οurous It's indeed too verbose: a->b->{var L=java.util.stream.IntStream.range(a,b).boxed().collect(java.util.Collectors.toList());L.add(0,b);L.add(0,a);return L;} (130 bytes) – Kevin Cruijssen Nov 8 at 12:11
  • Is it Java 8 or Java 10 ? Because of "var" ^^' – Neyt Nov 9 at 10:45
  • 1
    @Neyt Ah, fixed. My initial version with the array below didn't use var, which is why I usually put those at 8, and the ones that does use var as 10 (and the ones using String.repeat as 11). :) Forgot to update it after adding the List and String answers, should be corrected now. Thanks. – Kevin Cruijssen Nov 9 at 10:51

Haskell, 34 bytes

a#b=a:b:[a+1..b-1]++[a-1,a-2..b+1]

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  • This does not work. GHC interprets b-1 as b $ (-1). Use b- 1 instead. – Mark Neu 2 days ago
  • @MarkNeu: it does work. See TIO link. – nimi 2 days ago
  • Oh, sorry! I had NegativeLiterals on. – Mark Neu 2 days ago

Jelly, 4 bytes

,œ|r

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How it works

,œ|r  Main link. Left argument: a. Right argument: b

,     Pair; yield [a, b].
   r  Range; yield [a, ..., b].
 œ|   Perform multiset union.

J, 26 bytes

,,[|.@]^:(>{.)<.+1}.i.@|@-

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Explanation:

A dyadic verb (takes left and right argument)

                         -    subtracts the arguments
                       |@     and finds the absolute value
                    i.@       and makes a list 0..absolute difference
                 1}.          drops the fist element
                +             adds to the entire list
              <.              the smaller of the arguments
   |.@]                       reverses the list
       ^:                     only if
  [                           the left argument
         (>{.)                is greater than the first item of the list
 ,                            appends the list to
,                             the right argument appended to the left one
  • 1
    ,,[:}.@}:<.+i.@-@(+*)@- for 23 bytes and no special casing on relative argument ordering (rather: it's hidden inside the signum *). i feel like this could get down under 20 but i'm tired. – Jonah 2 days ago
  • @Jonah Thank you! Btw FrownyFrog's solution is way better than mine, so I 'm not going to golf it any further. – Galen Ivanov 2 days ago

Octave, 45 bytes

@(a,b)[a b linspace(a,b,(t=abs(a-b))+1)(2:t)]

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  • IF the first is larger than the second, the range must be descending – TFeld Nov 8 at 11:03
  • Oh man, I can't read – Luis Mendo Nov 8 at 11:03
  • I ended up changing the language – Luis Mendo Nov 8 at 14:33

J, 13 bytes

,,<.+i.@-~-.=

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     i.@-~       range [0 .. |difference|-1], reverse if the difference is positive
          -.=    remove the zero (either "=" is 0 or there’s nothing to remove)
  <.+            to each element add the smaller of the args
,,               prepend args
  • Nice solution! I totally forgot abouti. with negative argument. – Galen Ivanov Nov 8 at 17:40
  • 1
    this is gorgeous! – Jonah 2 days ago

Batch, 107 bytes

@echo %1
@echo %2
@for %%s in (1 -1)do @for /l %%i in (%1,%%s,%2)do @if %1 neq %%i if %%i neq %2 echo %%i

Takes input as command-line arguments. Explanation:

@echo %1
@echo %2

Output the two integers.

@for %%s in (1 -1)do

Try both ascending and descending ranges.

@for /l %%i in (%1,%%s,%2)do

Loop over the inclusive range.

@if %1 neq %%i if %%i neq %2

Exclude the two integers.

echo %%i

Output the current value.

Pyth, 5 bytes

+QtrF

Input is a two-element list, [input 1, input 2]. Try it online here, or verify all the test cases at once here.

+QtrFQ   Implicit: Q=eval(input())
         Trailing Q inferred
   rFQ   Generate range [input 1 - input 2)
  t      Discard first element
+Q       Prepend Q
  • Using F instead of .* on 2-element lists is a brilliant trick that I will absolutely be using from here on. – hakr14 Nov 8 at 16:31

Red, 75 bytes

func[a b][s: sign? d: b - a prin[a b]loop absolute d - s[prin[""a: a + s]]]

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Clean, 49 bytes

import StdEnv
@a b=init[a,b:tl[a,a+sign(b-a)..b]]

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Python 2, 52 47 41 bytes

lambda i,j:[i,j]+range(i,j,(i<j)*2-1)[1:]

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-5 with thanks to @JoKing

-6 by slicing the first element from the range (idea stolen from and with credit to @TFeld)

Non-lambda version...

Python 2, 51 49 47 bytes

i,j=input();print[i,j]+range(i,j,(i<j)*2-1)[1:]

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-2 with thanks to @JoKing

APL (Dyalog Classic), 29 bytes

{⍺,⍵,(⌽⍣(⍺>⍵))(⍺⌊⍵)+¯1↓⍳|⍺-⍵}

Try it online!

A port of my J solution

  • Wow, I'm surprised this is so long for a seemingly simple task. – Quintec Nov 9 at 0:43
  • @Quintec Probably it can be golfed, or maybe another algorithm will result in much shorter solution. – Galen Ivanov Nov 9 at 4:35

PHP (102 bytes)

function t($a,$b){count($r=range($a,$b))>1?array_splice($r,1,0,array_pop($r)):$r=[$a,$b];print_r($r);}

Sandbox

Unfortunately (for golf) PHP has rather verbose function names, which contribute a lot to the length. But the basic idea is to create a range, then pop off the last element and stitch it back in at offset 1. For the 4,4 example I had to add count($r=range($a,$b))>1?...:$r=[$a,$b]; which adds quite a bit, and unfortunately array_splice() is by reference which hit me for a few more bytes ($r= and a ;). All because of that "edge case", lol.

Well anyway enjoy!

  • I dont think that this is a right approach for code golf. Check this one function t($a,$b){$o=array($a,$b);for($i=$a+1;$i<$b;$i++)$o[]=$i;print_r($o);} – th3pirat3 2 days ago
  • Or something like this function t($a,$b){echo $a.$b;for($i=$a+1;$i<$b;$i++)echo $i}; – th3pirat3 2 days ago
  • 1
    It has to be a function and it has to output an array. If you have a better answer your more then welcome to post it. – ArtisticPhoenix 2 days ago
  • I edited it, is that a valid submission now? Shall I put it as a new answer or what? – th3pirat3 2 days ago
  • That is entirely up to you, I just wanted to do it without a loop ... lol – ArtisticPhoenix 2 days ago

D, 85 bytes

T[]f(T)(T a,T b){T[]v=[a,b];T c=2*(b>a)-1;for(T i=a+c;a!=b&&b!=i;i+=c)v~=i;return v;}

Try it online!

A port of @HatsuPointerKun's C++ answer into D.

TI-BASIC, 35 34 bytes

-1 byte from Misha Lavrov

Prompt A,B
Disp A,B
cos(π(A>B
For(I,A+Ans,B-Ans,Ans
Disp I
End
  • 2
    And one more byte by replacing 1-2(A>B with cos(π(A>B. – Misha Lavrov Nov 8 at 20:55
  • @MishaLavrov seq( wouldn't work for inputs where A and B are the same, unfortunately :( – kamoroso94 Nov 8 at 22:33
  • True - also, I left out an argument of seq(, so I'm no longer convinced it even is smaller. Still, the cos( trick should help. – Misha Lavrov Nov 8 at 22:34

Charcoal, 15 bytes

IE²NI…⊕θηI⮌…⊕ηθ

Try it online! Link is to verbose version of code. Explanation:

IE²N

Print the inputs on separate lines.

I…⊕θη

Print the ascending range, if any.

I⮌…⊕ηθ

Print the reverse ascending reverse range, if any.

Dart, 85 84 bytes

f(a,b)=>[a,b]+((a-b).abs()>1?List.generate((a-b).abs()-1,(i)=>(a>b?-i-1:i+1)+a):[]);

Try it online!

  • -1 by going from >= to >

    QBASIC, 39 53 bytes

    INPUT a,b
    ?a
    ?b
    FOR q=a+1TO b-1 STEP SGN(b-a)
    ?q
    NEXT
    

    Added the STEP parameter to account for a>b, and that uses the SGN() function to get a -1 or a +1 as increment. This however breaks the REPL because the SGN() function isn't implemented there...

    Try it (the old answer) online!

    Ruby, 33 40 bytes

    ->a,b{[a,b]+[*a..b,*a.downto(b)][1..-2]}
    

    Try it online!

    Temporary fix, trying to find a better idea

    • 3
      For [4,4] this gives only one [4] – Kirill L. Nov 8 at 9:36

    C (gcc), 65 bytes

    f(a,b){for(printf("%d %d",a,b);a<b?++a<b:--a>b;)printf(" %d",a);}
    

    Try it online!

    Not very exciting. The loop increment is borrowed from an early version of Kevin Cruijssen's Java answer.

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