Greatest common substring












4












$begingroup$


Create a program or function which takes a list of strings as input, and outputs the longest string that is a substring of all input strings. If there are several substrings of equal length, and no longer substring, output any one of them.




  • This may mean outputting the empty string.

  • If there are several valid outputs, you may output any one of them. You are not required to give consistent outpput for a given input so long as the output is always valid.

  • There will always be at least one string in the input, but there might not be a non-empty string.

  • All printable ASCII characters may appear in the input. You may assume those are the only characters that appear.

  • You may take input or produce output by any of the default methods.


  • Standard loopholes aren't allowed.

  • This is code-golf - the fewer bytes of code, the better.


Test cases:



[Inputs] -> [Valid outputs (choose one)]



["hello", "'ello"] -> ["ello"]
["very", "much", "different"] -> [""]
["empty", "", "STRING"] -> [""]
["identical", "identical"] -> ["identical"]
["string", "stRIng"] -> ["st", "ng"]
["this one", "is a substring of this one"] -> ["this one"]
["just one"] -> ["just one"]
["", "", ""] -> [""]
["many outputs", "stuptuo ynam"] -> ["m", "a", "n", "y", " ", "o", "u", "t", "p", "s"]
["many inputs", "any inputs", "ny iii", "yanny"] -> ["ny"]
["%%not&", "ju&#st", "[&]alpha_numeric"] -> ["%"]









share|improve this question











$endgroup$












  • $begingroup$
    Possible duplicate
    $endgroup$
    – Adám
    1 hour ago










  • $begingroup$
    @Adám That question asks for the longest common subsequence, not substring.
    $endgroup$
    – Doorknob
    1 hour ago






  • 1




    $begingroup$
    Will the strings be only alphanumeric, or alphabetic, or only printable-ascii?
    $endgroup$
    – Embodiment of Ignorance
    20 mins ago










  • $begingroup$
    @EmbodimentofIgnorance All printable ASCII characters can appear in the input.
    $endgroup$
    – Sara J
    6 mins ago
















4












$begingroup$


Create a program or function which takes a list of strings as input, and outputs the longest string that is a substring of all input strings. If there are several substrings of equal length, and no longer substring, output any one of them.




  • This may mean outputting the empty string.

  • If there are several valid outputs, you may output any one of them. You are not required to give consistent outpput for a given input so long as the output is always valid.

  • There will always be at least one string in the input, but there might not be a non-empty string.

  • All printable ASCII characters may appear in the input. You may assume those are the only characters that appear.

  • You may take input or produce output by any of the default methods.


  • Standard loopholes aren't allowed.

  • This is code-golf - the fewer bytes of code, the better.


Test cases:



[Inputs] -> [Valid outputs (choose one)]



["hello", "'ello"] -> ["ello"]
["very", "much", "different"] -> [""]
["empty", "", "STRING"] -> [""]
["identical", "identical"] -> ["identical"]
["string", "stRIng"] -> ["st", "ng"]
["this one", "is a substring of this one"] -> ["this one"]
["just one"] -> ["just one"]
["", "", ""] -> [""]
["many outputs", "stuptuo ynam"] -> ["m", "a", "n", "y", " ", "o", "u", "t", "p", "s"]
["many inputs", "any inputs", "ny iii", "yanny"] -> ["ny"]
["%%not&", "ju&#st", "[&]alpha_numeric"] -> ["%"]









share|improve this question











$endgroup$












  • $begingroup$
    Possible duplicate
    $endgroup$
    – Adám
    1 hour ago










  • $begingroup$
    @Adám That question asks for the longest common subsequence, not substring.
    $endgroup$
    – Doorknob
    1 hour ago






  • 1




    $begingroup$
    Will the strings be only alphanumeric, or alphabetic, or only printable-ascii?
    $endgroup$
    – Embodiment of Ignorance
    20 mins ago










  • $begingroup$
    @EmbodimentofIgnorance All printable ASCII characters can appear in the input.
    $endgroup$
    – Sara J
    6 mins ago














4












4








4





$begingroup$


Create a program or function which takes a list of strings as input, and outputs the longest string that is a substring of all input strings. If there are several substrings of equal length, and no longer substring, output any one of them.




  • This may mean outputting the empty string.

  • If there are several valid outputs, you may output any one of them. You are not required to give consistent outpput for a given input so long as the output is always valid.

  • There will always be at least one string in the input, but there might not be a non-empty string.

  • All printable ASCII characters may appear in the input. You may assume those are the only characters that appear.

  • You may take input or produce output by any of the default methods.


  • Standard loopholes aren't allowed.

  • This is code-golf - the fewer bytes of code, the better.


Test cases:



[Inputs] -> [Valid outputs (choose one)]



["hello", "'ello"] -> ["ello"]
["very", "much", "different"] -> [""]
["empty", "", "STRING"] -> [""]
["identical", "identical"] -> ["identical"]
["string", "stRIng"] -> ["st", "ng"]
["this one", "is a substring of this one"] -> ["this one"]
["just one"] -> ["just one"]
["", "", ""] -> [""]
["many outputs", "stuptuo ynam"] -> ["m", "a", "n", "y", " ", "o", "u", "t", "p", "s"]
["many inputs", "any inputs", "ny iii", "yanny"] -> ["ny"]
["%%not&", "ju&#st", "[&]alpha_numeric"] -> ["%"]









share|improve this question











$endgroup$




Create a program or function which takes a list of strings as input, and outputs the longest string that is a substring of all input strings. If there are several substrings of equal length, and no longer substring, output any one of them.




  • This may mean outputting the empty string.

  • If there are several valid outputs, you may output any one of them. You are not required to give consistent outpput for a given input so long as the output is always valid.

  • There will always be at least one string in the input, but there might not be a non-empty string.

  • All printable ASCII characters may appear in the input. You may assume those are the only characters that appear.

  • You may take input or produce output by any of the default methods.


  • Standard loopholes aren't allowed.

  • This is code-golf - the fewer bytes of code, the better.


Test cases:



[Inputs] -> [Valid outputs (choose one)]



["hello", "'ello"] -> ["ello"]
["very", "much", "different"] -> [""]
["empty", "", "STRING"] -> [""]
["identical", "identical"] -> ["identical"]
["string", "stRIng"] -> ["st", "ng"]
["this one", "is a substring of this one"] -> ["this one"]
["just one"] -> ["just one"]
["", "", ""] -> [""]
["many outputs", "stuptuo ynam"] -> ["m", "a", "n", "y", " ", "o", "u", "t", "p", "s"]
["many inputs", "any inputs", "ny iii", "yanny"] -> ["ny"]
["%%not&", "ju&#st", "[&]alpha_numeric"] -> ["%"]






code-golf string subsequence






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited 1 min ago







Sara J

















asked 1 hour ago









Sara JSara J

1715




1715












  • $begingroup$
    Possible duplicate
    $endgroup$
    – Adám
    1 hour ago










  • $begingroup$
    @Adám That question asks for the longest common subsequence, not substring.
    $endgroup$
    – Doorknob
    1 hour ago






  • 1




    $begingroup$
    Will the strings be only alphanumeric, or alphabetic, or only printable-ascii?
    $endgroup$
    – Embodiment of Ignorance
    20 mins ago










  • $begingroup$
    @EmbodimentofIgnorance All printable ASCII characters can appear in the input.
    $endgroup$
    – Sara J
    6 mins ago


















  • $begingroup$
    Possible duplicate
    $endgroup$
    – Adám
    1 hour ago










  • $begingroup$
    @Adám That question asks for the longest common subsequence, not substring.
    $endgroup$
    – Doorknob
    1 hour ago






  • 1




    $begingroup$
    Will the strings be only alphanumeric, or alphabetic, or only printable-ascii?
    $endgroup$
    – Embodiment of Ignorance
    20 mins ago










  • $begingroup$
    @EmbodimentofIgnorance All printable ASCII characters can appear in the input.
    $endgroup$
    – Sara J
    6 mins ago
















$begingroup$
Possible duplicate
$endgroup$
– Adám
1 hour ago




$begingroup$
Possible duplicate
$endgroup$
– Adám
1 hour ago












$begingroup$
@Adám That question asks for the longest common subsequence, not substring.
$endgroup$
– Doorknob
1 hour ago




$begingroup$
@Adám That question asks for the longest common subsequence, not substring.
$endgroup$
– Doorknob
1 hour ago




1




1




$begingroup$
Will the strings be only alphanumeric, or alphabetic, or only printable-ascii?
$endgroup$
– Embodiment of Ignorance
20 mins ago




$begingroup$
Will the strings be only alphanumeric, or alphabetic, or only printable-ascii?
$endgroup$
– Embodiment of Ignorance
20 mins ago












$begingroup$
@EmbodimentofIgnorance All printable ASCII characters can appear in the input.
$endgroup$
– Sara J
6 mins ago




$begingroup$
@EmbodimentofIgnorance All printable ASCII characters can appear in the input.
$endgroup$
– Sara J
6 mins ago










4 Answers
4






active

oldest

votes


















0












$begingroup$


Jelly, 12 bytes



Ẇ€œ&/LÐṀḢ¹L?


Try it online!



Last four bytes are there because of the requirement to only output one answer.






share|improve this answer









$endgroup$





















    0












    $begingroup$

    Not golfed it much yet but here's my Python 3 answer at 354 bytes:

    EDIT: Now 238 bytes with one space indents and some one-line iterators:

    EDIT: 193 bytes with max function

    EDIT: 189 bytes removed unnecessary list



    def a(b):
    a=();c=list(sum(list(list(d[f:e]for f in range(e))for e in range(len(d)+1)),)for d in b)
    for i in c[0]:
    if all(i in j for j in c):
    a+=(i,)
    return max(a,key=len)





    share|improve this answer










    New contributor




    Artemis Fowl is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.






    $endgroup$













    • $begingroup$
      You may want to use single spaces as indentation instead of 4 that seems to shave more than 100 bytes.
      $endgroup$
      – Shieru Asakoto
      56 mins ago










    • $begingroup$
      @ShieruAsakoto Oops yeah.
      $endgroup$
      – Artemis Fowl
      49 mins ago










    • $begingroup$
      135 bytes by simplifying the c declaration and condensing the for loop. I would recommend adding the title and bytecount to the header, or using TIO's formatter to create the body of your post
      $endgroup$
      – Jo King
      20 mins ago












    • $begingroup$
      102 bytes by using set operators instead
      $endgroup$
      – Jo King
      15 mins ago



















    0












    $begingroup$


    JavaScript (Node.js), 114 105 bytes





    a=>(F=(l,n,w=a[0].substr(n,l))=>l?n<0?F(--l,L-l):a.some(y=>y.search(w)<0)?F(l,n-1):w:"")(L=a[0].length,0)


    Try it online!



    Probably still golfable.
    y.indexOf must be used in place of y.search if the strings may contain special regex characters, at the cost of 1 more byte.






    share|improve this answer











    $endgroup$





















      0












      $begingroup$


      Brachylog (v2), 3 bytes



      sᵛw


      Try it online!



      Full program. Input from standard input (as a JSON-style list of strings), output to standard output.



      Explanation



      sᵛw
      s Find a substring
      ᵛ of every element {of the input}; the same one for each
      w and output it.


      Tiebreak order here is set by the s, favouring the longest substring (the secondary tiebreak doesn't matter, but IIRC it's position within the first element of the input).



      Brachylog's s doesn't return empty substrings, so we need a bit of a trick to get around that: instead of making a function submission (which is what's normally done), we write a full program, outputting to standard output. That way, if there's a common substring, we just output it, and we're done. If there isn't a common substring, the program errors out – but it still prints nothing to standard output, thus it outputs the null string as intended.






      share|improve this answer











      $endgroup$













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        4 Answers
        4






        active

        oldest

        votes








        4 Answers
        4






        active

        oldest

        votes









        active

        oldest

        votes






        active

        oldest

        votes









        0












        $begingroup$


        Jelly, 12 bytes



        Ẇ€œ&/LÐṀḢ¹L?


        Try it online!



        Last four bytes are there because of the requirement to only output one answer.






        share|improve this answer









        $endgroup$


















          0












          $begingroup$


          Jelly, 12 bytes



          Ẇ€œ&/LÐṀḢ¹L?


          Try it online!



          Last four bytes are there because of the requirement to only output one answer.






          share|improve this answer









          $endgroup$
















            0












            0








            0





            $begingroup$


            Jelly, 12 bytes



            Ẇ€œ&/LÐṀḢ¹L?


            Try it online!



            Last four bytes are there because of the requirement to only output one answer.






            share|improve this answer









            $endgroup$




            Jelly, 12 bytes



            Ẇ€œ&/LÐṀḢ¹L?


            Try it online!



            Last four bytes are there because of the requirement to only output one answer.







            share|improve this answer












            share|improve this answer



            share|improve this answer










            answered 1 hour ago









            Nick KennedyNick Kennedy

            92147




            92147























                0












                $begingroup$

                Not golfed it much yet but here's my Python 3 answer at 354 bytes:

                EDIT: Now 238 bytes with one space indents and some one-line iterators:

                EDIT: 193 bytes with max function

                EDIT: 189 bytes removed unnecessary list



                def a(b):
                a=();c=list(sum(list(list(d[f:e]for f in range(e))for e in range(len(d)+1)),)for d in b)
                for i in c[0]:
                if all(i in j for j in c):
                a+=(i,)
                return max(a,key=len)





                share|improve this answer










                New contributor




                Artemis Fowl is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                Check out our Code of Conduct.






                $endgroup$













                • $begingroup$
                  You may want to use single spaces as indentation instead of 4 that seems to shave more than 100 bytes.
                  $endgroup$
                  – Shieru Asakoto
                  56 mins ago










                • $begingroup$
                  @ShieruAsakoto Oops yeah.
                  $endgroup$
                  – Artemis Fowl
                  49 mins ago










                • $begingroup$
                  135 bytes by simplifying the c declaration and condensing the for loop. I would recommend adding the title and bytecount to the header, or using TIO's formatter to create the body of your post
                  $endgroup$
                  – Jo King
                  20 mins ago












                • $begingroup$
                  102 bytes by using set operators instead
                  $endgroup$
                  – Jo King
                  15 mins ago
















                0












                $begingroup$

                Not golfed it much yet but here's my Python 3 answer at 354 bytes:

                EDIT: Now 238 bytes with one space indents and some one-line iterators:

                EDIT: 193 bytes with max function

                EDIT: 189 bytes removed unnecessary list



                def a(b):
                a=();c=list(sum(list(list(d[f:e]for f in range(e))for e in range(len(d)+1)),)for d in b)
                for i in c[0]:
                if all(i in j for j in c):
                a+=(i,)
                return max(a,key=len)





                share|improve this answer










                New contributor




                Artemis Fowl is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                Check out our Code of Conduct.






                $endgroup$













                • $begingroup$
                  You may want to use single spaces as indentation instead of 4 that seems to shave more than 100 bytes.
                  $endgroup$
                  – Shieru Asakoto
                  56 mins ago










                • $begingroup$
                  @ShieruAsakoto Oops yeah.
                  $endgroup$
                  – Artemis Fowl
                  49 mins ago










                • $begingroup$
                  135 bytes by simplifying the c declaration and condensing the for loop. I would recommend adding the title and bytecount to the header, or using TIO's formatter to create the body of your post
                  $endgroup$
                  – Jo King
                  20 mins ago












                • $begingroup$
                  102 bytes by using set operators instead
                  $endgroup$
                  – Jo King
                  15 mins ago














                0












                0








                0





                $begingroup$

                Not golfed it much yet but here's my Python 3 answer at 354 bytes:

                EDIT: Now 238 bytes with one space indents and some one-line iterators:

                EDIT: 193 bytes with max function

                EDIT: 189 bytes removed unnecessary list



                def a(b):
                a=();c=list(sum(list(list(d[f:e]for f in range(e))for e in range(len(d)+1)),)for d in b)
                for i in c[0]:
                if all(i in j for j in c):
                a+=(i,)
                return max(a,key=len)





                share|improve this answer










                New contributor




                Artemis Fowl is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                Check out our Code of Conduct.






                $endgroup$



                Not golfed it much yet but here's my Python 3 answer at 354 bytes:

                EDIT: Now 238 bytes with one space indents and some one-line iterators:

                EDIT: 193 bytes with max function

                EDIT: 189 bytes removed unnecessary list



                def a(b):
                a=();c=list(sum(list(list(d[f:e]for f in range(e))for e in range(len(d)+1)),)for d in b)
                for i in c[0]:
                if all(i in j for j in c):
                a+=(i,)
                return max(a,key=len)






                share|improve this answer










                New contributor




                Artemis Fowl is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                Check out our Code of Conduct.









                share|improve this answer



                share|improve this answer








                edited 24 mins ago





















                New contributor




                Artemis Fowl is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                Check out our Code of Conduct.









                answered 59 mins ago









                Artemis FowlArtemis Fowl

                1013




                1013




                New contributor




                Artemis Fowl is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                Check out our Code of Conduct.





                New contributor





                Artemis Fowl is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                Check out our Code of Conduct.






                Artemis Fowl is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
                Check out our Code of Conduct.












                • $begingroup$
                  You may want to use single spaces as indentation instead of 4 that seems to shave more than 100 bytes.
                  $endgroup$
                  – Shieru Asakoto
                  56 mins ago










                • $begingroup$
                  @ShieruAsakoto Oops yeah.
                  $endgroup$
                  – Artemis Fowl
                  49 mins ago










                • $begingroup$
                  135 bytes by simplifying the c declaration and condensing the for loop. I would recommend adding the title and bytecount to the header, or using TIO's formatter to create the body of your post
                  $endgroup$
                  – Jo King
                  20 mins ago












                • $begingroup$
                  102 bytes by using set operators instead
                  $endgroup$
                  – Jo King
                  15 mins ago


















                • $begingroup$
                  You may want to use single spaces as indentation instead of 4 that seems to shave more than 100 bytes.
                  $endgroup$
                  – Shieru Asakoto
                  56 mins ago










                • $begingroup$
                  @ShieruAsakoto Oops yeah.
                  $endgroup$
                  – Artemis Fowl
                  49 mins ago










                • $begingroup$
                  135 bytes by simplifying the c declaration and condensing the for loop. I would recommend adding the title and bytecount to the header, or using TIO's formatter to create the body of your post
                  $endgroup$
                  – Jo King
                  20 mins ago












                • $begingroup$
                  102 bytes by using set operators instead
                  $endgroup$
                  – Jo King
                  15 mins ago
















                $begingroup$
                You may want to use single spaces as indentation instead of 4 that seems to shave more than 100 bytes.
                $endgroup$
                – Shieru Asakoto
                56 mins ago




                $begingroup$
                You may want to use single spaces as indentation instead of 4 that seems to shave more than 100 bytes.
                $endgroup$
                – Shieru Asakoto
                56 mins ago












                $begingroup$
                @ShieruAsakoto Oops yeah.
                $endgroup$
                – Artemis Fowl
                49 mins ago




                $begingroup$
                @ShieruAsakoto Oops yeah.
                $endgroup$
                – Artemis Fowl
                49 mins ago












                $begingroup$
                135 bytes by simplifying the c declaration and condensing the for loop. I would recommend adding the title and bytecount to the header, or using TIO's formatter to create the body of your post
                $endgroup$
                – Jo King
                20 mins ago






                $begingroup$
                135 bytes by simplifying the c declaration and condensing the for loop. I would recommend adding the title and bytecount to the header, or using TIO's formatter to create the body of your post
                $endgroup$
                – Jo King
                20 mins ago














                $begingroup$
                102 bytes by using set operators instead
                $endgroup$
                – Jo King
                15 mins ago




                $begingroup$
                102 bytes by using set operators instead
                $endgroup$
                – Jo King
                15 mins ago











                0












                $begingroup$


                JavaScript (Node.js), 114 105 bytes





                a=>(F=(l,n,w=a[0].substr(n,l))=>l?n<0?F(--l,L-l):a.some(y=>y.search(w)<0)?F(l,n-1):w:"")(L=a[0].length,0)


                Try it online!



                Probably still golfable.
                y.indexOf must be used in place of y.search if the strings may contain special regex characters, at the cost of 1 more byte.






                share|improve this answer











                $endgroup$


















                  0












                  $begingroup$


                  JavaScript (Node.js), 114 105 bytes





                  a=>(F=(l,n,w=a[0].substr(n,l))=>l?n<0?F(--l,L-l):a.some(y=>y.search(w)<0)?F(l,n-1):w:"")(L=a[0].length,0)


                  Try it online!



                  Probably still golfable.
                  y.indexOf must be used in place of y.search if the strings may contain special regex characters, at the cost of 1 more byte.






                  share|improve this answer











                  $endgroup$
















                    0












                    0








                    0





                    $begingroup$


                    JavaScript (Node.js), 114 105 bytes





                    a=>(F=(l,n,w=a[0].substr(n,l))=>l?n<0?F(--l,L-l):a.some(y=>y.search(w)<0)?F(l,n-1):w:"")(L=a[0].length,0)


                    Try it online!



                    Probably still golfable.
                    y.indexOf must be used in place of y.search if the strings may contain special regex characters, at the cost of 1 more byte.






                    share|improve this answer











                    $endgroup$




                    JavaScript (Node.js), 114 105 bytes





                    a=>(F=(l,n,w=a[0].substr(n,l))=>l?n<0?F(--l,L-l):a.some(y=>y.search(w)<0)?F(l,n-1):w:"")(L=a[0].length,0)


                    Try it online!



                    Probably still golfable.
                    y.indexOf must be used in place of y.search if the strings may contain special regex characters, at the cost of 1 more byte.







                    share|improve this answer














                    share|improve this answer



                    share|improve this answer








                    edited 19 mins ago

























                    answered 29 mins ago









                    Shieru AsakotoShieru Asakoto

                    2,750317




                    2,750317























                        0












                        $begingroup$


                        Brachylog (v2), 3 bytes



                        sᵛw


                        Try it online!



                        Full program. Input from standard input (as a JSON-style list of strings), output to standard output.



                        Explanation



                        sᵛw
                        s Find a substring
                        ᵛ of every element {of the input}; the same one for each
                        w and output it.


                        Tiebreak order here is set by the s, favouring the longest substring (the secondary tiebreak doesn't matter, but IIRC it's position within the first element of the input).



                        Brachylog's s doesn't return empty substrings, so we need a bit of a trick to get around that: instead of making a function submission (which is what's normally done), we write a full program, outputting to standard output. That way, if there's a common substring, we just output it, and we're done. If there isn't a common substring, the program errors out – but it still prints nothing to standard output, thus it outputs the null string as intended.






                        share|improve this answer











                        $endgroup$


















                          0












                          $begingroup$


                          Brachylog (v2), 3 bytes



                          sᵛw


                          Try it online!



                          Full program. Input from standard input (as a JSON-style list of strings), output to standard output.



                          Explanation



                          sᵛw
                          s Find a substring
                          ᵛ of every element {of the input}; the same one for each
                          w and output it.


                          Tiebreak order here is set by the s, favouring the longest substring (the secondary tiebreak doesn't matter, but IIRC it's position within the first element of the input).



                          Brachylog's s doesn't return empty substrings, so we need a bit of a trick to get around that: instead of making a function submission (which is what's normally done), we write a full program, outputting to standard output. That way, if there's a common substring, we just output it, and we're done. If there isn't a common substring, the program errors out – but it still prints nothing to standard output, thus it outputs the null string as intended.






                          share|improve this answer











                          $endgroup$
















                            0












                            0








                            0





                            $begingroup$


                            Brachylog (v2), 3 bytes



                            sᵛw


                            Try it online!



                            Full program. Input from standard input (as a JSON-style list of strings), output to standard output.



                            Explanation



                            sᵛw
                            s Find a substring
                            ᵛ of every element {of the input}; the same one for each
                            w and output it.


                            Tiebreak order here is set by the s, favouring the longest substring (the secondary tiebreak doesn't matter, but IIRC it's position within the first element of the input).



                            Brachylog's s doesn't return empty substrings, so we need a bit of a trick to get around that: instead of making a function submission (which is what's normally done), we write a full program, outputting to standard output. That way, if there's a common substring, we just output it, and we're done. If there isn't a common substring, the program errors out – but it still prints nothing to standard output, thus it outputs the null string as intended.






                            share|improve this answer











                            $endgroup$




                            Brachylog (v2), 3 bytes



                            sᵛw


                            Try it online!



                            Full program. Input from standard input (as a JSON-style list of strings), output to standard output.



                            Explanation



                            sᵛw
                            s Find a substring
                            ᵛ of every element {of the input}; the same one for each
                            w and output it.


                            Tiebreak order here is set by the s, favouring the longest substring (the secondary tiebreak doesn't matter, but IIRC it's position within the first element of the input).



                            Brachylog's s doesn't return empty substrings, so we need a bit of a trick to get around that: instead of making a function submission (which is what's normally done), we write a full program, outputting to standard output. That way, if there's a common substring, we just output it, and we're done. If there isn't a common substring, the program errors out – but it still prints nothing to standard output, thus it outputs the null string as intended.







                            share|improve this answer














                            share|improve this answer



                            share|improve this answer








                            answered 16 mins ago


























                            community wiki





                            ais523































                                draft saved

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                                If this is an answer to a challenge…




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                                  Explanations of your answer make it more interesting to read and are very much encouraged.


                                • …Include a short header which indicates the language(s) of your code and its score, as defined by the challenge.



                                More generally…




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