Implement Magic Dictionary
<p>Design a data structure that is initialized with a list of <strong>different</strong> words. Provided a string, you should determine if you can change exactly one character in this string to match any word in the data structure.</p>

<p>Implement the&nbsp;<code>MagicDictionary</code>&nbsp;class:</p>

<ul>
	<li><code>MagicDictionary()</code>&nbsp;Initializes the object.</li>
	<li><code>void buildDict(String[]&nbsp;dictionary)</code>&nbsp;Sets the data structure&nbsp;with an array of distinct strings <code>dictionary</code>.</li>
	<li><code>bool search(String searchWord)</code> Returns <code>true</code> if you can change <strong>exactly one character</strong> in <code>searchWord</code> to match any string in the data structure, otherwise returns <code>false</code>.</li>
</ul>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input</strong>
[&quot;MagicDictionary&quot;, &quot;buildDict&quot;, &quot;search&quot;, &quot;search&quot;, &quot;search&quot;, &quot;search&quot;]
[[], [[&quot;hello&quot;, &quot;leetcode&quot;]], [&quot;hello&quot;], [&quot;hhllo&quot;], [&quot;hell&quot;], [&quot;leetcoded&quot;]]
<strong>Output</strong>
[null, null, false, true, false, false]

<strong>Explanation</strong>
MagicDictionary magicDictionary = new MagicDictionary();
magicDictionary.buildDict([&quot;hello&quot;, &quot;leetcode&quot;]);
magicDictionary.search(&quot;hello&quot;); // return False
magicDictionary.search(&quot;hhllo&quot;); // We can change the second &#39;h&#39; to &#39;e&#39; to match &quot;hello&quot; so we return True
magicDictionary.search(&quot;hell&quot;); // return False
magicDictionary.search(&quot;leetcoded&quot;); // return False
</pre>

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

<ul>
	<li><code>1 &lt;=&nbsp;dictionary.length &lt;= 100</code></li>
	<li><code>1 &lt;=&nbsp;dictionary[i].length &lt;= 100</code></li>
	<li><code>dictionary[i]</code> consists of only lower-case English letters.</li>
	<li>All the strings in&nbsp;<code>dictionary</code>&nbsp;are <strong>distinct</strong>.</li>
	<li><code>1 &lt;=&nbsp;searchWord.length &lt;= 100</code></li>
	<li><code>searchWord</code>&nbsp;consists of only lower-case English letters.</li>
	<li><code>buildDict</code>&nbsp;will be called only once before <code>search</code>.</li>
	<li>At most <code>100</code> calls will be made to <code>search</code>.</li>
</ul>
Depth-First Search; Design; Trie; Hash Table; String
class Trie {
    private Trie[] children = new Trie[26];
    private boolean isEnd;

    public void insert(String w) {
        Trie node = this;
        for (char c : w.toCharArray()) {
            int i = c - 'a';
            if (node.children[i] == null) {
                node.children[i] = new Trie();
            }
            node = node.children[i];
        }
        node.isEnd = true;
    }

    public boolean search(String w) {
        return dfs(w, 0, this, 0);
    }

    private boolean dfs(String w, int i, Trie node, int diff) {
        if (i == w.length()) {
            return diff == 1 && node.isEnd;
        }
        int j = w.charAt(i) - 'a';
        if (node.children[j] != null) {
            if (dfs(w, i + 1, node.children[j], diff)) {
                return true;
            }
        }
        if (diff == 0) {
            for (int k = 0; k < 26; k++) {
                if (k != j && node.children[k] != null) {
                    if (dfs(w, i + 1, node.children[k], 1)) {
                        return true;
                    }
                }
            }
        }
        return false;
    }
}

class MagicDictionary {
    private Trie trie = new Trie();

    public MagicDictionary() {
    }

    public void buildDict(String[] dictionary) {
        for (String w : dictionary) {
            trie.insert(w);
        }
    }

    public boolean search(String searchWord) {
        return trie.search(searchWord);
    }
}

/**
 * Your MagicDictionary object will be instantiated and called as such:
 * MagicDictionary obj = new MagicDictionary();
 * obj.buildDict(dictionary);
 * boolean param_2 = obj.search(searchWord);
 */