reverse words in a string - April practice

reverseWordsInAString_AprilPractice.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace reverseWordsInMay
{
    /// <summary>
    /// April, 2017 
    /// Should use in place swap, do not use extra space 
    /// </summary>
    class Program
    {
        static void Main(string[] args)
        {
            var result = ReverseOrderOfWordsLinearScan(new char[]{'a',' ','b', ' ','c'}, ' '); 
        }

        public static char[] ReverseOrderOfWordsLinearScan(char[] words, char delimiter)
        {
            string reversedWord = string.Empty; 
            if(words == null || words.Length == 0) 
            {
                return reversedWord.ToCharArray(); 
            }
   
            int length = words.Length;               
   
            reverseString(words, 0, length - 1);    
                     
           // space "  aaa", skip first few spaces 
           int start = 0; 
           int end = 0; 
           for(int i = 0; i < length; i++)
           {
              char current = words[i]; 
              if(current != delimiter)
              {
                 end = i;                          
              }
              else if(current == delimiter)
              {
                 if(end > start)
                 {
                     reverseString(words, start, end); 
                     start = i + 1; 
                     end   = i + 1; 
                 }
                 else 
                 {
                    start = i+1; 
                    end = i+1; 
                 }
              }
            }

           return words;
        }

        // O(n)
        // char[]  output- char[]
        // char[] -> string-> char[]
        // char [ a, b, c] -> i=0, j=2 swap() -> k=char[0]=a, char[
        // return char[]
        // in place - swap both end < 
        private static void reverseString(char[] words, int start, int end)
        {
            while (start < end)
            {   
                var tmp = words[start];
                words[start] = words[end];
                words[end] = tmp; 

                start++;
                end--;
            }           
        }
    }
}