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A
afzalk0001
August 9, 2023
Question

Josephus Problem

  • August 9, 2023
  • 15 replies
  • 0 views

100 people standing in a circle in an order 1 to 100. No. 1 has a sword. He kills the next person (i.e. No. 2) and gives the sword to the next (i.e. No. 3). All people do the same until only 1 survives. Which number survives at the last? 
There are 100 people starting from 1 to 100. 

can anyone please tell me how can i do it?

    15 replies

    richardm900458
    richardm900458
    August 9, 2023

    Thats no appian related question, is it ;)?

      A
      afzalk0001Author
      August 9, 2023

      No just wanted to try using appian. Whether is it possible using expressuin rules or not?

      stefanhelzle0001
      stefanhelzle0001
      August 9, 2023

      You can implement recursive and iterative algorithms. So, the answer is: Yes!

      mathieud0001
      mathieud0001
      August 9, 2023

      Is this some sort of exam question?

      A
      afzalk0001Author
      August 9, 2023

      Yeah its a puzzle problem. You can refer this - https://www.geeksforgeeks.org/puzzle-100-people-in-a-circle-with-gun-puzzle/

      i was just trying to implement using appian.

      csteward
      csteward
      August 9, 2023

      This is my example with a recursive rule to solve the puzzle (#73).

      As always, make sure to save recursive rules before testing.

      /* rule!chris_test_kc_recur(
      list (Number Array, 1+enumerate(100))
      index (Number, 1)
   )
*/

if(
  count(ri!list)<=1,
  index(ri!list,1,null),
  a!localVariables(
    local!removeIndex: if(
      ri!index=count(ri!list),
      1,
      if(
        ri!index>count(ri!list),
        2,
        ri!index+1
      )
    ),
    local!list: remove(ri!list,local!removeIndex),
    rule!chris_test_kc_recur(
      list: local!list,
      index: local!removeIndex
    )
  )
)

        A
        afzalk0001Author
        August 10, 2023

        can you please share me the code rule!chris_test_kc_recur? That would be helpful

        richardm900458
        richardm900458
        August 10, 2023

        why not trying yourself than getting it served already prepared? :) The question was , if it was possible. yes it is. :)

        jamesm4933
        jamesm4933
        August 10, 2023

        It's called the Josephus Problem.  It was inspired by a story in "The Jewish War" by Flavius Josephus.

        Apparently, the solutions for n=2 up to group size 78 are sequence number A006257 in the On-line Encyclopedia of Integer Sequences

        Wikipedia

        The Jewish War

        nikhilcht188835
        nikhilcht188835
        August 11, 2023

        Here is the solution to your challenge. We have also added a feather so that the user may choose the number of players and who should start the game.

        reduce(
  rule!EI_subEliminateTask(list: _, value: _),
  {
    ldrop(
      enumerate(ri!players) + 1,
      ri!startPlayer - 1
    ),
    if(
      ri!startPlayer = 1,
      {},
      enumerate(ri!startPlayer - 1) + 1
    )
  },
  repeat(ri!players - 1, 0)
)

subrule: rule!EI_subEliminateTask(list: _, value: _),
code: { ldrop(ri!list, 2), ri!list[1] }

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