using System;

using System.Collections.Generic;

using System.Linq;

using System.Text.RegularExpressions;

​

namespace ConsoleTest

{

  class Program

  {

    static void Main(string[] args)

    {

      Dictionary<string, string> dict = new Dictionary<string, string>

      {

        { "A",  "DD" },

        { "BB",  "C" },

        { "DD",  "ABC" },

        { "CCCDD", "VVV" }

      };

      string previouslyString = " ZLKMVBEJbb CCCCDDD ddDD";

​

      var processing = new ProcessingRight();

      string result = processing.Run(previouslyString, dict);

​

      Console.WriteLine(result);

      //Console.ReadKey();

    }

  }

}

​

namespace ConsoleTest

{

  // RIGHT WAY FOR PROCESSING TASK //

  public class ProcessingRight

  {

    public string Run(string input, Dictionary<string, string> inputDict)

    {

      var resultList = new List<string>();

      char[] array = input.ToArray();

      string prevSymbols = string.Empty;

​

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

      {

        string replaceValue = GetReplaceValue(input, inputDict, array[i], ref i);

​

        resultList.Add(replaceValue);

​

        continue;

      }

​

      string result = string.Join("", resultList.ToArray());

​

      return result;

    }

​

    /// <summary>

    /// Gets the replace value.

    /// </summary>

    /// <param name="input">The input.</param>

    /// <param name="inputDict">The input dictionary.</param>

    /// <param name="current">The char arrays current element.</param>

    /// <param name="index">The array index.</param>

    private string GetReplaceValue(string input, Dictionary<string, string> inputDict, char current, ref int index)

    {

      string currentStr = current.ToString();

​

      // find if current char is part of template

      string pattern = string.Format(@"^{0}", currentStr);

​

      foreach (var item in inputDict)

      {

        string template = item.Key;

        bool isMatch = Regex.IsMatch(template, pattern);

        if (isMatch)

        {

          // to avoid exception: index out of range

          if (index + template.Length > input.Length)

          {

            return currentStr;

          }

​

          // processing exact right template

          string piece = input.Substring(index, template.Length);

          if (template == piece)

          {

            index = index + template.Length - 1;

​

            return item.Value;

          }

        }

      }

​

      return currentStr;

    }

  }

}

​