using System;

​

    namespace ConsoleApplication1

    {

        public class Program

        {

            public static void Main(string[] args)

            {

                //                                                                                      1

                ulong a = Convert.ToUInt64("0000000000000000000000000000000000000000000000000000000000001101", 2);

                ulong b = Convert.ToUInt64("1110010101100101011001010110110101100101011001010110010101100101", 2);

​

                Console.WriteLine(dendrite(a, 4, b));

​

            }

​

            private static float dendrite(ulong mask, int len, ulong input)

            {

                return 1 - getBitCount(mask ^ (input & (ulong.MaxValue >> (64 - len)))) / (float)len;            

            }

​

            private static ulong getBitCount(ulong bits)

            {

                bits = bits - ((bits >> 1) & 0x5555555555555555UL);

                bits = (bits & 0x3333333333333333UL) + ((bits >> 2) & 0x3333333333333333UL);

                return unchecked(((bits + (bits >> 4)) & 0xF0F0F0F0F0F0F0FUL) * 0x101010101010101UL) >> 56;

            }

        }

    }

​