using System;

/*

function FMHash(obj, CaseInsensitive)

        {            

            let hash1 = 42;//prime

            let hash2 = 42;//prime            

            for(let i = 0; i < obj.length; ++i)

            {

                const ch = CaseInsensitive ?  obj.charAt(i).toLowerCase() : obj.charAt(i);

                if (/\s/.test(ch))

                {

                    ++hash2;

                    continue;

                }                

                hash1 += ch.charCodeAt(0) * (1 + i - hash2);

            }

            return hash1 + hash2 - obj.length;

        }

*/

​

public class Program

{

    public static void Main()

    {

        GetHashCode("a b").Dump();

        GetHashCode("ab").Dump();

        GetHashCode(" a b").Dump();

        GetHashCode("a b ").Dump();

    }

    public static int GetHashCode(string obj, bool CaseInsensitive = false)

        {

            unchecked

            {

                int hash1 = 42;

                int wsc = 42;

                for(int i = 0; i < obj.Length; ++i)

                {

                    char ch = CaseInsensitive ? char.ToLowerInvariant(obj[i]) : obj[i];

                    if (char.IsWhiteSpace(ch))

                    {

                        ++wsc;

                        continue;

                    }

                    int c = ch.GetHashCode() * (1 + i - wsc);

                    hash1 += c;

                }

                return hash1 + wsc - obj.Length;

            }

        }

}