211. Design Add and Search Words Data Structure

class WordDictionary 
{
    private TrieNode root; 
    public WordDictionary() 
    {
        root = new TrieNode();
    }
    public void addWord(String word) 
    {
        TrieNode node = root;
        for (char c: word.toCharArray())
        {
            if(node.children[c - 'a'] == null)
            {
                node.children[c - 'a'] = new TrieNode();
            }
            node = node.children[c - 'a'];
        }
        node.val = word;
    }

    public boolean search(String word) 
               {
        return match(word, 0, root);
    }

    private boolean match(String word, int depth, TrieNode node)
    {
        if(depth == word.length()) 
            return !node.val.equals("");
        if(word.charAt(depth) != '.')
        {
            return (node.children[word.charAt(depth) - 'a'] != null && match(word, depth + 1, node.children[word.charAt(depth) - 'a'] ));
        }
        else
        {
            for (int i = 0; i < node.children.length; i++)
            {
                if(node.children[i] != null && match(word, depth + 1, node.children[i]))
                    return true;
            }
        }
        return false;
    }
}
class TrieNode
{
    public TrieNode [] children = new TrieNode[26];
    public String val = "";
}

/**
 * Your WordDictionary object will be instantiated and called as such:
 * WordDictionary obj = new WordDictionary();
 * obj.addWord(word);
 * boolean param_2 = obj.search(word);
 */