Josephus Problem in Mathematica

Welcome to the Josephus Problem in Mathematica page! Here, you'll find the source code for this program as well as a description of how the program works.

Current Solution

(* Code *)

(* The code is trivial: *)

josephus[1, _] := 1
josephus[n_Integer, k_Integer] := Mod[josephus[n - 1, k] + (k - 1), n] + 1

(* The outer function provides the 'user interface': *)

josephusMain = Function[{people, skip},
   Catch[
    Module[{e = "Usage: please input the total number of people and number of people to skip."},
     josephus @@ Map[
       (* convert string to integer, or throw *)
       s \[Function] If[StringMatchQ[s, DigitCharacter ..],
         Module[{v = FromDigits[s]},
          If[Positive[v], v, Throw[e]]],(* make sure both numbers are positive *)
         Throw[e]],
       {people, skip}]]]];


(* Valid Tests *)

Print /@ Apply[josephusMain] /@ {
    {"5", "2"},
    {"7", "3"},
    {"41", "4"}
    };


(* Invalid Tests *)

josephusMain["", ""]
josephusMain["word", "word"]
josephusMain["0", "1"]

Josephus Problem in Mathematica was written by:

• Ben Hekster

If you see anything you'd like to change or update, please consider contributing.

How to Implement the Solution

No 'How to Implement the Solution' section available. Please consider contributing.

How to Run the Solution

No 'How to Run the Solution' section available. Please consider contributing.