using System;

using System.Text.RegularExpressions;

using System.Collections;

​

public class OpenRentStringParsing

{

    // takes string input and returns a string stripped of all special characters. ('a.b/-c' --> 'abc')

    public static string CleanString(string str)

    {

        // found a regex from stackoverflow to identify all special characters

        string cleaned_string = Regex.Replace(str, "[^0-9a-zA-Z]+", "");

        return cleaned_string;

    }

​

    // takes a string input and returns a reversed version of the string. ('abc' --> 'cba')

    public static string ReverseString(string str)

    {

        if (str.Length == 0)

        {

            return "";

        }

        string orig_str = str;

        string reversed_str = "";

        for (int i = orig_str.Length - 1; i >= 0; i--)

        {

            reversed_str += orig_str[i];

        }

        return reversed_str;

    }

    // takes a string input and returns the earliest character in the alphabet ('yzx' --> 'x')

    public static char EarliestChar(string str)

    {

​

        if (str.Length == 0)

        {

            return '\0';

        }

        char current_earliest_char = 'z';

        foreach (char character in str)

        {

            int char_num = (int) character % 32;

            int current_earliest_char_num = (int) current_earliest_char % 32;

            if (char_num < current_earliest_char_num)

            {

            current_earliest_char = character;

            }

        }

        return current_earliest_char;

    }

    // takes a string input, counts the number of vowels and returns true if that number is even, false if odd ('abc' --> true)

    public static bool EvenNumberOfVowels(string str)

    {

        var vowels = new ArrayList()

                        {

                            "a","e","i","o","u"

                        };

        int count = 0;

        foreach(char character in str)

        {

            // found String.Contains method on c# docs

            if (vowels.Contains(character))

            {

                count += 1;

            }

        }

        if (count % 2 == 0)

        {

            return true;

        }

        else

        {

            return false;

        }

    }

    // combines the above methods to parse the string as per the requirements given in the question

    public static string ParseString(string str)

    {

        string output = "";

        string cleaned_string = CleanString(str);

        output += ReverseString(cleaned_string);

        output += EarliestChar(cleaned_string);

        if (EvenNumberOfVowels(cleaned_string) == false)

        {

            output += "open";

        }

        else

        {

            output += "rent";

        }

        return output;

    }

    public static void Main(String[] args)

    {

        string input = "nepo";

        string output = ParseString(input);

        Console.WriteLine(output);

    }

}

// Had this been in a real live environment I would have created some unit tests to test these functions

// before writing them, but as I can't run this code it seemed unnecessary (and not helpful)

// e.g. for CleanString() I would provide multiple edge cases (empty input, large input, etc)

// and assert that the result of this function is what I would expect.

​

// to test the example edge case: with input 'nepo'

// ParseString(nepo):

// output = ''

// CleanString('nepo') = 'nepo'

// output += ReverseString('nepo') //(output = 'open')

// output += EarliestChar('nepo') //(output = 'opene')

// EvenNumberOfVowels('nepo') = true

// output += 'rent' //(output = 'openerent')

// return output ('openerent')

// Future optimisations: Can I do this without iterating through the string so many times?

// Probably, but I opted for a cleaner modular approach to separate out the logic.

// if required, I could probably combine these into a singular pass through of the string but the

//code

// wouldn't have been anywhere near as clean.

​

// Hopefully this exercise has demonstrated my logical structured and modular approach to a coding problem...

// I apologise for the syntax, I've never really touched c# before and mostly code in Python.

// I was looking at https://learnxinyminutes.com/docs/csharp/ whilst writing this and learning syntax on the fly.

// Looking forward to speaking soon and recieving feedback. Thanks :)