Find median of a circular set

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Given a set of elements and a number $k$, each element is as a disc has a number from $0$ to $k-1$ written around its circumference. Consecutive numbers are adjacent to each other, i.e., $1$ is between $0$ and $2$, and because the discs are circular, $0$ is between $k-1$ and $1$.



Discs can rotate freely in either direction, we can only rotate one disc at a time, and it takes $1$ second to rotate it by one position) find the smallest number we should choose to make all elements equal and that number costs minimum steps.



E.g.: set = $[2,7,1]$, $k = 10$; the output should be $1$.



It takes $1$ step for the first element to reach $1$ $(2 to 1)$.
It takes $4$ steps for the second element to reach $1$ $(7 to 8 to 9 to 0 to 1)$. The third element is already at $1$.



I tried to find the median but it do not work out (or may be i find it wrong) and although sometime the steps is minimum but the number is not.



Is finding median of a circle is answer for this problem, if it is not, what should anothor approach should I consider?







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    Given a set of elements and a number $k$, each element is as a disc has a number from $0$ to $k-1$ written around its circumference. Consecutive numbers are adjacent to each other, i.e., $1$ is between $0$ and $2$, and because the discs are circular, $0$ is between $k-1$ and $1$.



    Discs can rotate freely in either direction, we can only rotate one disc at a time, and it takes $1$ second to rotate it by one position) find the smallest number we should choose to make all elements equal and that number costs minimum steps.



    E.g.: set = $[2,7,1]$, $k = 10$; the output should be $1$.



    It takes $1$ step for the first element to reach $1$ $(2 to 1)$.
    It takes $4$ steps for the second element to reach $1$ $(7 to 8 to 9 to 0 to 1)$. The third element is already at $1$.



    I tried to find the median but it do not work out (or may be i find it wrong) and although sometime the steps is minimum but the number is not.



    Is finding median of a circle is answer for this problem, if it is not, what should anothor approach should I consider?







    share|cite|improve this question























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      Given a set of elements and a number $k$, each element is as a disc has a number from $0$ to $k-1$ written around its circumference. Consecutive numbers are adjacent to each other, i.e., $1$ is between $0$ and $2$, and because the discs are circular, $0$ is between $k-1$ and $1$.



      Discs can rotate freely in either direction, we can only rotate one disc at a time, and it takes $1$ second to rotate it by one position) find the smallest number we should choose to make all elements equal and that number costs minimum steps.



      E.g.: set = $[2,7,1]$, $k = 10$; the output should be $1$.



      It takes $1$ step for the first element to reach $1$ $(2 to 1)$.
      It takes $4$ steps for the second element to reach $1$ $(7 to 8 to 9 to 0 to 1)$. The third element is already at $1$.



      I tried to find the median but it do not work out (or may be i find it wrong) and although sometime the steps is minimum but the number is not.



      Is finding median of a circle is answer for this problem, if it is not, what should anothor approach should I consider?







      share|cite|improve this question













      Given a set of elements and a number $k$, each element is as a disc has a number from $0$ to $k-1$ written around its circumference. Consecutive numbers are adjacent to each other, i.e., $1$ is between $0$ and $2$, and because the discs are circular, $0$ is between $k-1$ and $1$.



      Discs can rotate freely in either direction, we can only rotate one disc at a time, and it takes $1$ second to rotate it by one position) find the smallest number we should choose to make all elements equal and that number costs minimum steps.



      E.g.: set = $[2,7,1]$, $k = 10$; the output should be $1$.



      It takes $1$ step for the first element to reach $1$ $(2 to 1)$.
      It takes $4$ steps for the second element to reach $1$ $(7 to 8 to 9 to 0 to 1)$. The third element is already at $1$.



      I tried to find the median but it do not work out (or may be i find it wrong) and although sometime the steps is minimum but the number is not.



      Is finding median of a circle is answer for this problem, if it is not, what should anothor approach should I consider?









      share|cite|improve this question












      share|cite|improve this question




      share|cite|improve this question








      edited Jul 24 at 13:30









      Rodrigo de Azevedo

      12.6k41751




      12.6k41751









      asked Jul 24 at 13:00









      Zac Jonathan

      545




      545

























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