Factorial in Beef

Welcome to the Factorial 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 Factorial;

class Program
{
    public static void Usage()
    {
        Console.WriteLine("Usage: please input a non-negative integer");
        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);
    }

    public static Result<uint64> Factorial(int32 n)
    {
        uint64 result = 1;
        for (int32 i in 2...n)
        {
            if (result > (uint64.MaxValue / (uint64)i))
            {
                return .Err;
            }

            result *= (uint64)i;
        }

        return .Ok(result);
    }

    public static int Main(String[] args)
    {
        if (args.Count < 1)
        {
            Usage();
        }

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

        uint64 result = 0;
        switch (Factorial(val))
        {
            case .Ok(out result):
                Console.WriteLine(result);
            case .Err:
                Console.WriteLine("Overflow!");
        }

        return 0;
    }
}

Factorial 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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