Josephus Problem in Beef

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

Current Solution

using System;

namespace JosephusProblem;

class Program
{
    public static void Usage()
    {
        Console.WriteLine("Usage: please input the total number of people and number of people to skip.");
        Environment.Exit(0);
    }

    public static Result<T> ParseInt<T>(StringView str)
    where T : IParseable<T>
    {
        StringView trimmedStr = scope String(str);
        trimmedStr.Trim();

        // T.Parse ignores single quotes since they are treat as digit separators -- e.g. 1'000
        if (trimmedStr.Contains('\''))
        {
            return .Err;
        }

        return T.Parse(trimmedStr);
    }

    // Reference: https://en.wikipedia.org/wiki/Josephus_problem#The_general_case
    //
    // Use zero-based index algorithm:
    //
    //    g(1, k) = 0
    //    g(m, k) = [g(m - 1, k) + k] MOD m, for m = 2, 3, ..., n
    //
    // Final answer is g(n, k) + 1 to get back to one-based index
    public static T JosephusProblem<T>(T n, T k)
    where T : IInteger, operator explicit int, operator T + T, operator T % T
    where int : operator T <=> T, operator explicit T
    {
        T g = (T)0;
        for (T m = (T)2; m <= n; m += (T)1)
        {
            g = (g + k) % m;
        }

        return g + (T)1;
    }

    public static int Main(String[] args)
    {
        if (args.Count < 2)
        {
            Usage();
        }

        int32 n = 0;
        switch (ParseInt<int32>(args[0]))
        {
            case .Ok(out n):
            case .Err:
                Usage();
        }

        int32 k = 0;
        switch (ParseInt<int32>(args[1]))
        {
            case .Ok(out k):
            case .Err:
                Usage();
        }

        int32 result = JosephusProblem<int32>(n, k);
        Console.WriteLine(result);
        return 0;
    }
}

Josephus Problem in Beef was written by:

• rzuckerm

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

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