Solution Review: List Sort Using Tries

using System;
using System.Collections.Generic;
using System.Text;
namespace chapter_7
{
    class Program
    {
        static void getWords(TrieNode root, List<string>  result, int level, ref string word)
        {
            //Leaf denotes end of a word
            if (root.isEndWord)
            {
                //current word is stored till the 'level' in the word string
                string temp = "";
               
                for (int x = 0; x < level; x++)
                {
                    temp += word[x];
                }
                result.Add(temp);
               
            }
            for (int i = 0; i < 26; i++)
            {
                if (root.children[i] != null)
                {
                    if(level < word.Length)
                    {
                        StringBuilder sb = new StringBuilder(word);
                        sb[level] = (char)(i + 'a');
                        word = sb.ToString();
                    }
                    else
                    {
                        word += (char)(i + 'a');
                    }
                    
                    getWords(root.children[i], result, level + 1, ref word);
                }
            }
        }
        static List<string> sortArray(string [] arr, int arr_length)
        {
            List<string> result = new List<string>();
            //Creating Trie and Inserting words from array
            Trie trie = new Trie();
            for (int x = 0; x < arr_length; x++)
                trie.insertNode(arr[x]);
            string str = string.Empty;
            getWords(trie.getRoot(), result, 0, ref str);
            return result;
        }
       
        static void Main(string[] args)
        {
            string []keys = { "the", "a", "there", "answer", "any", "by", "bye", "their", "abc" };
            List<string> ans = sortArray(keys, 9);
            for (int i = 0; i < ans.Count; i++)
            {
                Console.WriteLine(ans[i]);
            }
            return;
        }
    }
}