Expand and Contract












6












$begingroup$


Take a positive integer $k$ as input. Start with $n := 1$ and repeatedly increase $n$ by the largest integer power of ten $i$ such that $i le n$ and $i + n le k$.



Repeat until $n = k$ and return a list of all intermediate values of $n$, including both the initial $1$ and the final $k$.



During this process, growth will initially be limited by the former inequality, and only afterwards by the latter; the growth will take the form of an initial "expansion" period, during which $n$ is increased by ever-larger powers, followed by a "contract" period, during which $n$ is increased by ever-smaller powers in order to "zoom in" on the correct number.



Test Cases



1 => [1]
10 => [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
321 => [1, 2, 3, 4, 5, 6, 7, 8, 9,
10, 20, 30, 40, 50, 60, 70, 80, 90,
100, 200, 300, 310, 320, 321]
1002 => [1, 2, 3, 4, 5, 6, 7, 8, 9,
10, 20, 30, 40, 50, 60, 70, 80, 90,
100, 200, 300, 400, 500, 600, 700, 800, 900,
1000, 1001, 1002]


This is code-golf, so the shortest answer (in bytes) wins.










share|improve this question









$endgroup$

















    6












    $begingroup$


    Take a positive integer $k$ as input. Start with $n := 1$ and repeatedly increase $n$ by the largest integer power of ten $i$ such that $i le n$ and $i + n le k$.



    Repeat until $n = k$ and return a list of all intermediate values of $n$, including both the initial $1$ and the final $k$.



    During this process, growth will initially be limited by the former inequality, and only afterwards by the latter; the growth will take the form of an initial "expansion" period, during which $n$ is increased by ever-larger powers, followed by a "contract" period, during which $n$ is increased by ever-smaller powers in order to "zoom in" on the correct number.



    Test Cases



    1 => [1]
    10 => [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
    321 => [1, 2, 3, 4, 5, 6, 7, 8, 9,
    10, 20, 30, 40, 50, 60, 70, 80, 90,
    100, 200, 300, 310, 320, 321]
    1002 => [1, 2, 3, 4, 5, 6, 7, 8, 9,
    10, 20, 30, 40, 50, 60, 70, 80, 90,
    100, 200, 300, 400, 500, 600, 700, 800, 900,
    1000, 1001, 1002]


    This is code-golf, so the shortest answer (in bytes) wins.










    share|improve this question









    $endgroup$















      6












      6








      6





      $begingroup$


      Take a positive integer $k$ as input. Start with $n := 1$ and repeatedly increase $n$ by the largest integer power of ten $i$ such that $i le n$ and $i + n le k$.



      Repeat until $n = k$ and return a list of all intermediate values of $n$, including both the initial $1$ and the final $k$.



      During this process, growth will initially be limited by the former inequality, and only afterwards by the latter; the growth will take the form of an initial "expansion" period, during which $n$ is increased by ever-larger powers, followed by a "contract" period, during which $n$ is increased by ever-smaller powers in order to "zoom in" on the correct number.



      Test Cases



      1 => [1]
      10 => [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
      321 => [1, 2, 3, 4, 5, 6, 7, 8, 9,
      10, 20, 30, 40, 50, 60, 70, 80, 90,
      100, 200, 300, 310, 320, 321]
      1002 => [1, 2, 3, 4, 5, 6, 7, 8, 9,
      10, 20, 30, 40, 50, 60, 70, 80, 90,
      100, 200, 300, 400, 500, 600, 700, 800, 900,
      1000, 1001, 1002]


      This is code-golf, so the shortest answer (in bytes) wins.










      share|improve this question









      $endgroup$




      Take a positive integer $k$ as input. Start with $n := 1$ and repeatedly increase $n$ by the largest integer power of ten $i$ such that $i le n$ and $i + n le k$.



      Repeat until $n = k$ and return a list of all intermediate values of $n$, including both the initial $1$ and the final $k$.



      During this process, growth will initially be limited by the former inequality, and only afterwards by the latter; the growth will take the form of an initial "expansion" period, during which $n$ is increased by ever-larger powers, followed by a "contract" period, during which $n$ is increased by ever-smaller powers in order to "zoom in" on the correct number.



      Test Cases



      1 => [1]
      10 => [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
      321 => [1, 2, 3, 4, 5, 6, 7, 8, 9,
      10, 20, 30, 40, 50, 60, 70, 80, 90,
      100, 200, 300, 310, 320, 321]
      1002 => [1, 2, 3, 4, 5, 6, 7, 8, 9,
      10, 20, 30, 40, 50, 60, 70, 80, 90,
      100, 200, 300, 400, 500, 600, 700, 800, 900,
      1000, 1001, 1002]


      This is code-golf, so the shortest answer (in bytes) wins.







      code-golf number decimal






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked 1 hour ago









      Esolanging FruitEsolanging Fruit

      8,65932774




      8,65932774






















          2 Answers
          2






          active

          oldest

          votes


















          2












          $begingroup$


          Python 2, 61 bytes





          f=lambda k,n=1:n<k and[n]+f(k,n+10**~-len(`min(n,k-n)`))or[n]


          Try it online!






          share|improve this answer











          $endgroup$





















            2












            $begingroup$


            Perl 6, 48 41 bytes





            ->k{1,{$_+10**min($_,k-$_).comb/10}...k}


            Try it online!



            Explanation:



            ->k{                                   }  # Anonymous code block taking k
            1, ...k # Start a sequence from 1 to k
            { } # Where each element is
            $_+ # The previous element plus
            10** # 10 to the power of
            .comb # The length of
            min($_,k-$_) # The min of the current count and the remainder
            /10 # Minus one





            share|improve this answer











            $endgroup$














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              2 Answers
              2






              active

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              2 Answers
              2






              active

              oldest

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              active

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              active

              oldest

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              2












              $begingroup$


              Python 2, 61 bytes





              f=lambda k,n=1:n<k and[n]+f(k,n+10**~-len(`min(n,k-n)`))or[n]


              Try it online!






              share|improve this answer











              $endgroup$


















                2












                $begingroup$


                Python 2, 61 bytes





                f=lambda k,n=1:n<k and[n]+f(k,n+10**~-len(`min(n,k-n)`))or[n]


                Try it online!






                share|improve this answer











                $endgroup$
















                  2












                  2








                  2





                  $begingroup$


                  Python 2, 61 bytes





                  f=lambda k,n=1:n<k and[n]+f(k,n+10**~-len(`min(n,k-n)`))or[n]


                  Try it online!






                  share|improve this answer











                  $endgroup$




                  Python 2, 61 bytes





                  f=lambda k,n=1:n<k and[n]+f(k,n+10**~-len(`min(n,k-n)`))or[n]


                  Try it online!







                  share|improve this answer














                  share|improve this answer



                  share|improve this answer








                  edited 31 mins ago

























                  answered 37 mins ago









                  Chas BrownChas Brown

                  5,0891523




                  5,0891523























                      2












                      $begingroup$


                      Perl 6, 48 41 bytes





                      ->k{1,{$_+10**min($_,k-$_).comb/10}...k}


                      Try it online!



                      Explanation:



                      ->k{                                   }  # Anonymous code block taking k
                      1, ...k # Start a sequence from 1 to k
                      { } # Where each element is
                      $_+ # The previous element plus
                      10** # 10 to the power of
                      .comb # The length of
                      min($_,k-$_) # The min of the current count and the remainder
                      /10 # Minus one





                      share|improve this answer











                      $endgroup$


















                        2












                        $begingroup$


                        Perl 6, 48 41 bytes





                        ->k{1,{$_+10**min($_,k-$_).comb/10}...k}


                        Try it online!



                        Explanation:



                        ->k{                                   }  # Anonymous code block taking k
                        1, ...k # Start a sequence from 1 to k
                        { } # Where each element is
                        $_+ # The previous element plus
                        10** # 10 to the power of
                        .comb # The length of
                        min($_,k-$_) # The min of the current count and the remainder
                        /10 # Minus one





                        share|improve this answer











                        $endgroup$
















                          2












                          2








                          2





                          $begingroup$


                          Perl 6, 48 41 bytes





                          ->k{1,{$_+10**min($_,k-$_).comb/10}...k}


                          Try it online!



                          Explanation:



                          ->k{                                   }  # Anonymous code block taking k
                          1, ...k # Start a sequence from 1 to k
                          { } # Where each element is
                          $_+ # The previous element plus
                          10** # 10 to the power of
                          .comb # The length of
                          min($_,k-$_) # The min of the current count and the remainder
                          /10 # Minus one





                          share|improve this answer











                          $endgroup$




                          Perl 6, 48 41 bytes





                          ->k{1,{$_+10**min($_,k-$_).comb/10}...k}


                          Try it online!



                          Explanation:



                          ->k{                                   }  # Anonymous code block taking k
                          1, ...k # Start a sequence from 1 to k
                          { } # Where each element is
                          $_+ # The previous element plus
                          10** # 10 to the power of
                          .comb # The length of
                          min($_,k-$_) # The min of the current count and the remainder
                          /10 # Minus one






                          share|improve this answer














                          share|improve this answer



                          share|improve this answer








                          edited 25 mins ago

























                          answered 49 mins ago









                          Jo KingJo King

                          26.3k364129




                          26.3k364129






























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