using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        Counter wordCounter = new Counter();

        Dictionary<String, int> result;

        String[] inputs = new String[] {null, "", "  ", "hi how are you?", "sheep sheep sheep sheep", "hi. hi, hi! hi?"};

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

        {

            bool success = wordCounter.WordCount("hi how are you", out result);

            switch (i)

            {

                case 0: // null

                    ValidationTeller(i, !success || result.Values.Count > 0 );

                    break;

                case 1: // ""

                    ValidationTeller(i, !success || result.Values.Count > 0 );

                    break;

                case 2: // "  "

                    ValidationTeller(i, !success || result.Values.Count > 0 );

                    break;

                case 3: // "hi how are you?"

                    ValidationTeller(i, !success || result.Values.Count != 4 );

                    break;

                case 4: // "sheep sheep sheep sheep"

                    int count;

                    ValidationTeller(i, !success || !result.TryGetValue("sheep", out count) || count != 4 );

                    break;

                case 5: // "hi. hi, hi! hi?"

                    ValidationTeller(i, !success || result.Values.Count != 4 );

                    break;

            }

        }

    }

    // reusable printout

    public static void ValidationTeller(int testNum, bool success)

    {

        String answer = "Test " + testNum;

        if (success)

            answer += " Passed!";

        else

            answer += " Failed...";

        Console.WriteLine(answer);

    }   

}

​

public class Counter

{   

    public bool WordCount(String input, out Dictionary<String, int> result) {

        // the result will always start as an empty dictionary

        result = new Dictionary<String, int>();

        // techincally, (assumption) nothing is "wrong" with a null input.

        // otherwise we could return false for null.

        if (input == null || input.TrimStart()Trim().Length == 0)

            return true;

        // Iterate over the string

        foreach (String word in input.Split())

        {

            int currCount;

            if (result.TryGetValue(word, out currCount))

                result.Add(word, currCount + 1);

            else

                result.Add(word, 1);

        }

        return true;

    }

}