混合字符串

https://www.codewars.com/kata/strings-mix/csharp

using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

public class Mixing 
{
  public static string Mix(string s1, string s2)
        {
            string mix = "";
            List<KeyValuePair<string, string>> mixlist = new List<KeyValuePair<string, string>>();

            s1 = Regex.Replace(s1, "[^a-z]", "");
            s2 = Regex.Replace(s2, "[^a-z]", "");

            string disStr1 = string.Join("", (from s in s1 where s1.Count(o => o == s) > 1 select s).Distinct().ToArray());
            string disStr2 = string.Join("", (from s in s2 where s2.Count(o => o == s) > 1 select s).Distinct().ToArray());

            for (int i = 0; i < disStr1.Length; i++)
            {
                int scount1 = s1.Count(o => o == disStr1[i]);
                int scount2 = s2.Count(o => o == disStr1[i]);
                string key = scount1 > scount2 ? "1" : scount1 < scount2 ? "2" : "3";
                string value = "";
                if (key == "1")
                {
                    for (int j = 0; j < scount1; j++)
                    {
                        value += disStr1[i];
                    }
                }
                else
                {
                    for (int k = 0; k < scount2; k++)
                    {
                        value += disStr1[i];
                    }
                }
                KeyValuePair<string,string> item = new KeyValuePair<string,string>(key,value);
                mixlist.Add(item);
                disStr2 = disStr2.Replace(disStr1[i].ToString(), "");
            }
            for (int i = 0; i < disStr2.Length; i++)
            {
                int scount2 = s2.Count(o => o == disStr2[i]);
                string key = "2";
                string value = "";

                for (int j = 0; j < scount2; j++)
                {
                    value += disStr2[i];
                }

                KeyValuePair<string, string> item = new KeyValuePair<string, string>(key, value);
                mixlist.Add(item);
            }

            var mixArr = (from l in mixlist orderby l.Value.Length descending,l.Key,l.Value select l).ToArray();

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

                mix += mixArr[i].Key + ":" + mixArr[i].Value + "/";

            }


            if(mix.Length > 0) 
            {
              mix = mix.Substring(0,mix.Length-1);
              mix = mix.Replace("3","=");
            }
            return mix;

        }
}