public class TrieNode {    public TrieNode[] Child {get;set;}    public bool EndWord {get;set;}    // Initialize your data structure here.    public TrieNode() {        Child = new TrieNode[26];        EndWord = false;    }}public class WordDictionary {    public TrieNode root  = new TrieNode();    // Adds a word into the data structure.    public void AddWord(String word) {        var sentinel = root;        foreach(char w in word)        {            if(sentinel.Child[w-‘a‘] == null) sentinel.Child[w-‘a‘] = new TrieNode();            sentinel = sentinel.Child[w-‘a‘];        }        sentinel.EndWord = true;            }    // Returns if the word is in the data structure. A word could    // contain the dot character ‘.‘ to represent any one letter.    public bool Search(string word) {        return Search(word,root,0);    }        public bool Search(string word, TrieNode t, int index)    {        if(index == word.Length) return t.EndWord;        if(word[index] == ‘.‘)        {            foreach(var c in t.Child)            {                if(c!= null && Search(word,c,index+1)) return true;            }            return false;        }        if(t== null ||t.Child[word[index]-‘a‘] == null) return false;        return Search(word,t.Child[word[index]-‘a‘],index+1);    }}// Your WordDictionary object will be instantiated and called as such:// WordDictionary wordDictionary = new WordDictionary();// wordDictionary.AddWord("word");// wordDictionary.Search("pattern");