// This program takes a string as input and converts it into a numerical value based on a custom decoding scheme.

// The decoding considers individual characters and specific two-character and four-character combinations.

​

using System;

using System.Collections.Generic;

using System.Linq;

​

// We define a custom class 'DecodeModel' to structure the output of our decoding process.

// This helps in organizing and understanding the intermediate steps.

public class DecodeModel

{

    public string SplitBy { get; set; } // Not used in the current implementation. Could be used for future extensions.

    public List<string> Input { get; set; } // Stores the input string as a list of individual characters.

    public List<string> Output { get; set; } // Stores the decoded segments of the input string.

    public List<string> Result { get; set; } // A temporary list, not actively used in the current logic.

​

    // Override ToString() method for easy debugging and visualization of the DecodeModel object.

    public override string ToString()

    {

        return $"SplitBy: {SplitBy}, Input: [{string.Join(",", Input)}], Output: [{string.Join(",", Output)}], Result: [{string.Join(",", Result)}]";

    }

}

​

public class Demo

{

    // The Main method is the entry point of our program.

    public static void Main()

    {

        // Declare a string variable to store the user's input.

        string inputValue;

​

        // Prompt the user to enter an input string.

        Console.WriteLine("Input: ");

​

        // Read the input string entered by the user from the console.

        inputValue = Console.ReadLine();

​

        // Remove any spaces from the input string to ensure correct processing.

        string processedValue = inputValue.Replace(" ", "");

​

        // Call the stringToNumber method to convert the processed input string into a number.

        int numericalOutput = StringToNumber(processedValue);

​

        // Display the original input string to the user.

        Console.WriteLine("Input: S = {0}", inputValue);

​

        // Display the calculated numerical output to the user.

        Console.WriteLine("Output = {0}", numericalOutput);

    }

​

    // This method converts a string into a list of individual characters.

    // For example, "ABCA" becomes ["A", "B", "C", "A"].

    static List<string> StringToList(string text)

    {

        // Convert the input string into an array of characters.

        char[] characterArray = text.ToCharArray();

​

        // Create a new list of strings to store individual characters.

        List<string> stringList = new List<string>();

​

        // Iterate through each character in the character array.

        foreach (char character in characterArray)

        {

            // Convert each character to a string and add it to the list.

            stringList.Add(character.ToString());

        }

​

        // Return the list of individual character strings.

        return stringList;

    }

​

    // This method decodes the input string based on defined patterns and returns a DecodeModel object.

    static DecodeModel DecoderText(string text)

    {

        // Instantiate a new DecodeModel object to store the decoding results.

        DecodeModel response = new DecodeModel();

​

        // Initialize temporary lists. 'tempList' is not actively used in the current implementation.

        List<string> tempList = new List<string>();

​

        // Initialize the 'finalList' which will hold the decoded segments of the input string.

        List<string> finalList = new List<string>();

​

        // A flag to indicate if the special sequence "AAAA" is present in the input string.

        bool containsAaaa = false;

​

        // Check if the input string contains the sequence "AAAA".

        if (text.Contains("AAAA"))

        {

            containsAaaa = true;

        }

​

        // Convert the input string into a list of individual characters for easier processing.

        List<string> textList = StringToList(text);

​

        // Iterate through the list of characters to identify and group decoding patterns.

        for (int i = 0; i < textList.Count; i++)

        {

            // 'nextIndex' helps to look ahead at the next character in the list.

            int nextIndex = i + 1;

​

            // Store the current character.

            string currentCharacter = textList[i];

​

            // Initialize an empty string for the next character.

            string nextCharacter = "";

​

            // Special handling for the "AAAA" sequence.

            if (containsAaaa)

            {

                // Calculate the indices of the next three characters.

                int nextIndex2 = i + 2;

                int nextIndex3 = i + 3;

​

                // Initialize an empty string to build a potential "AAAA" sequence.

                string potentialAaaa = "";

​

                // Check if there are enough characters remaining in the list to form "AAAA".

                if (nextIndex3 < textList.Count)

                {

                    // Construct the potential "AAAA" sequence.

                    potentialAaaa = currentCharacter + textList[nextIndex] + textList[nextIndex2] + textList[nextIndex3];

​

                    // If the constructed sequence is "AAAA".

                    if (potentialAaaa == "AAAA")

                    {

                        // Add "AAAA" to the 'finalList' as a decoded segment.

                        finalList.Add(potentialAaaa);

​

                        // Clear the characters that form "AAAA" in the 'textList' to avoid reprocessing them.

                        currentCharacter = "";

                        textList[nextIndex] = "";

                        textList[nextIndex2] = "";

                        textList[nextIndex3] = "";

                    }

                }

            }

​

            // Check if there is a next character available.

            if (nextIndex < textList.Count)

            {

                // Get the next character.

                nextCharacter = textList[nextIndex];

            }

​

            // Combine the current and next characters to check for two-character special sequences.

            string combinedCharacters = currentCharacter + nextCharacter;

​

            // Check if the combined characters form a special two-character sequence (like "AB", "AZ", etc.).

            if (CheckText(combinedCharacters))

            {

                // If it's a special sequence, add it to the 'finalList'.

                finalList.Add(combinedCharacters);

​

                // Clear the next character in 'textList' as it has been processed as part of the sequence.

                if (nextIndex < textList.Count)

                {

                    textList[nextIndex] = "";

                }

            }

            // If the combined characters are not a special sequence.

            else

            {

                // Add the current character to the 'finalList' as an individual segment.

                finalList.Add(currentCharacter);

            }

        }

​

        // Create a new list to store the final output, excluding any empty strings that might have resulted from the clearing process.

        List<string> outputList = new List<string>();

        for (int i = 0; i < finalList.Count; i++)

        {

            if (finalList[i] != "")

            {

                outputList.Add(finalList[i]);

            }

        }

​

        // Populate the properties of the DecodeModel object with the results.

        response.SplitBy = ""; // Not used.

        response.Input = textList; // Store the (modified) input character list.

        response.Output = outputList; // Store the list of decoded segments.

        response.Result = tempList; // Remains empty or unused.

​

        // Return the populated DecodeModel object.

        return response;

    }

​

    // This method checks if a given two-character string is a predefined special sequence.

    static bool CheckText(string text)

    {

        // Initialize the response to false.

        bool response = false;

​

        // Use a switch statement to efficiently check against multiple possible special sequences.

        switch (text)

        {

            case "AB":

                response = true;

                break;

            case "AZ":

                response = true;

                break;

            case "ZL":

                response = true;

                break;

            case "ZC":

                response = true;

                break;

            case "CD":

                response = true;

                break;

            case "CR":

                response = true;

                break;

        }

​

        // Return true if the input string matches one of the special sequences, false otherwise.

        return response;

    }

​

    // This method converts the decoded string segments into a final numerical value.

    static int StringToNumber(string text)

    {

        // Initialize the numerical value to 0.

        int value = 0;

​

        // Create a list to store the decoded segments.

        List<string> decodedSegmentsList = new List<string>();

​

        // Call the DecoderText method to get the decoded segments of the input string.

        DecodeModel decodedModel = DecoderText(text);

​

        // Add the decoded segments from the DecodeModel's Output property to our list.

        decodedSegmentsList.AddRange(decodedModel.Output);

​

        // Iterate through each decoded segment.

        for (int i = 0; i < decodedSegmentsList.Count; i++)

        {

            // Get the current decoded segment.

            string segment = decodedSegmentsList[i];

​

            // Initialize a variable to store the numerical value of the current segment.

            int segmentNumber = 0;

​

            // Use a switch statement to determine the numerical value of the segment based on the defined decoding rules.

            switch (segment)

            {

                case "A":

                    segmentNumber = 1;

                    break;

                case "B":

                    segmentNumber = 5;

                    break;

                case "Z":

                    segmentNumber = 10;

                    break;

                case "L":

                    segmentNumber = 50;

                    break;

                case "C":

                    segmentNumber = 100;

                    break;

                case "D":

                    segmentNumber = 500;

                    break;

                case "R":

                    segmentNumber = 1000;

                    break;

                case "AB":

                    segmentNumber = 4;

                    break;

                case "AZ":

                    segmentNumber = 9;

                    break;

                case "ZL":

                    segmentNumber = 40;

                    break;

                case "ZC":

                    segmentNumber = 90;

                    break;

                case "CD":

                    segmentNumber = 400;

                    break;

                case "CR":

                    segmentNumber = 900;

                    break;

                case "AAAA":

                    segmentNumber = 3;

                    break;

            }

​

            // Add the numerical value of the current segment to the total value.

            value += segmentNumber;

        }

​

        // Return the final calculated numerical value.

        return value;

    }

}