LeetCode 211. Add and Search Word – Data structure design

Add and Search Word – Data structure design

public class WordDictionary {
    class TrieNode {
        public TrieNode[] Children = new TrieNode[26];
        public bool IsWord = false;
    }
    
    TrieNode Root = new TrieNode();
    
    /** Initialize your data structure here. */
    public WordDictionary() {
        
    }
    
    /** Adds a word into the data structure. */
    public void AddWord(string word) {
        TrieNode cur = Root;
        for(int i = 0; i < word.Length; i++){
            int index = word[i] - 'a';
            if(cur.Children[index] == null) cur.Children[index] = new TrieNode();
            cur = cur.Children[index];
        }
        cur.IsWord = 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);
    }
    
    private bool Search(string word, TrieNode cur){
        char c = word[0];
        if(c != '.'){
            int index = c - 'a';
            if(cur.Children[index] == null) return false;
            cur = cur.Children[index];
            if(word.Length == 1){
                if(cur.IsWord) return true;
                else return false;
            } else {
                return Search(word.Substring(1), cur);
            }
        } else {
            for(int i = 0; i < 26; i++){
                if(cur.Children[i] == null) continue;
                if(word.Length == 1){
                    if(cur.Children[i].IsWord) return true;
                    else continue;
                }
                if(Search(word.Substring(1),cur.Children[i])) return true;
            }
            return false;
        }
    }
}

/**
 * Your WordDictionary object will be instantiated and called as such:
 * WordDictionary obj = new WordDictionary();
 * obj.AddWord(word);
 * bool param_2 = obj.Search(word);
 */