Design Add and Search Words Data Structure
<p>Design a data structure that supports adding new words and finding if a string matches any previously added string.</p>

<p>Implement the <code>WordDictionary</code> class:</p>

<ul>
	<li><code>WordDictionary()</code>&nbsp;Initializes the object.</li>
	<li><code>void addWord(word)</code> Adds <code>word</code> to the data structure, it can be matched later.</li>
	<li><code>bool search(word)</code>&nbsp;Returns <code>true</code> if there is any string in the data structure that matches <code>word</code>&nbsp;or <code>false</code> otherwise. <code>word</code> may contain dots <code>&#39;.&#39;</code> where dots can be matched with any letter.</li>
</ul>

<p>&nbsp;</p>
<p><strong class="example">Example:</strong></p>

<pre>
<strong>Input</strong>
[&quot;WordDictionary&quot;,&quot;addWord&quot;,&quot;addWord&quot;,&quot;addWord&quot;,&quot;search&quot;,&quot;search&quot;,&quot;search&quot;,&quot;search&quot;]
[[],[&quot;bad&quot;],[&quot;dad&quot;],[&quot;mad&quot;],[&quot;pad&quot;],[&quot;bad&quot;],[&quot;.ad&quot;],[&quot;b..&quot;]]
<strong>Output</strong>
[null,null,null,null,false,true,true,true]

<strong>Explanation</strong>
WordDictionary wordDictionary = new WordDictionary();
wordDictionary.addWord(&quot;bad&quot;);
wordDictionary.addWord(&quot;dad&quot;);
wordDictionary.addWord(&quot;mad&quot;);
wordDictionary.search(&quot;pad&quot;); // return False
wordDictionary.search(&quot;bad&quot;); // return True
wordDictionary.search(&quot;.ad&quot;); // return True
wordDictionary.search(&quot;b..&quot;); // return True
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= word.length &lt;= 25</code></li>
	<li><code>word</code> in <code>addWord</code> consists of lowercase English letters.</li>
	<li><code>word</code> in <code>search</code> consist of <code>&#39;.&#39;</code> or lowercase English letters.</li>
	<li>There will be at most <code>2</code> dots in <code>word</code> for <code>search</code> queries.</li>
	<li>At most <code>10<sup>4</sup></code> calls will be made to <code>addWord</code> and <code>search</code>.</li>
</ul>
Depth-First Search; Design; Trie; String
class Trie:
    def __init__(self):
        self.children = [None] * 26
        self.is_end = False


class WordDictionary:
    def __init__(self):
        self.trie = Trie()

    def addWord(self, word: str) -> None:
        node = self.trie
        for c in word:
            idx = ord(c) - ord('a')
            if node.children[idx] is None:
                node.children[idx] = Trie()
            node = node.children[idx]
        node.is_end = True

    def search(self, word: str) -> bool:
        def search(word, node):
            for i in range(len(word)):
                c = word[i]
                idx = ord(c) - ord('a')
                if c != '.' and node.children[idx] is None:
                    return False
                if c == '.':
                    for child in node.children:
                        if child is not None and search(word[i + 1 :], child):
                            return True
                    return False
                node = node.children[idx]
            return node.is_end

        return search(word, self.trie)


# Your WordDictionary object will be instantiated and called as such:
# obj = WordDictionary()
# obj.addWord(word)
# param_2 = obj.search(word)
