Package g0201_0300.s0208_implement_trie_prefix_tree

Class Trie

java.lang.Object

g0201_0300.s0208_implement_trie_prefix_tree.Trie

public class Trie
extends Object

208 - Implement Trie (Prefix Tree).<p>Medium</p> <p>A <a href="https://en.wikipedia.org/wiki/Trie" target="_top"><strong>trie</strong></a> (pronounced as &ldquo;try&rdquo;) or <strong>prefix tree</strong> is a tree data structure used to efficiently store and retrieve keys in a dataset of strings. There are various applications of this data structure, such as autocomplete and spellchecker.</p> <p>Implement the Trie class:</p> <ul> <li><code>Trie()</code> Initializes the trie object.</li> <li><code>void insert(String word)</code> Inserts the string <code>word</code> into the trie.</li> <li><code>boolean search(String word)</code> Returns <code>true</code> if the string <code>word</code> is in the trie (i.e., was inserted before), and <code>false</code> otherwise.</li> <li><code>boolean startsWith(String prefix)</code> Returns <code>true</code> if there is a previously inserted string <code>word</code> that has the prefix <code>prefix</code>, and <code>false</code> otherwise.</li> </ul> <p><strong>Example 1:</strong></p> <p><strong>Input</strong></p> <pre><code> [&quot;Trie&quot;, &quot;insert&quot;, &quot;search&quot;, &quot;search&quot;, &quot;startsWith&quot;, &quot;insert&quot;, &quot;search&quot;] [ [], [&quot;apple&quot;], [&quot;apple&quot;], [&quot;app&quot;], [&quot;app&quot;], [&quot;app&quot;], [&quot;app&quot;]] </code></pre> <p><strong>Output:</strong> [null, null, true, false, true, null, true]</p> <p><strong>Explanation:</strong></p> <pre><code> Trie trie = new Trie(); trie.insert(&quot;apple&quot;); trie.search(&quot;apple&quot;); // return True trie.search(&quot;app&quot;); // return False trie.startsWith(&quot;app&quot;); // return True trie.insert(&quot;app&quot;); trie.search(&quot;app&quot;); // return True </code></pre> <p><strong>Constraints:</strong></p> <ul> <li><code>1 <= word.length, prefix.length <= 2000</code></li> <li><code>word</code> and <code>prefix</code> consist only of lowercase English letters.</li> <li>At most <code>3 * 10⁴</code> calls <strong>in total</strong> will be made to <code>insert</code>, <code>search</code>, and <code>startsWith</code>.</li> </ul>

Constructor Summary

Constructors

Constructor	Description
Trie()

Method Summary

Modifier and Type	Method	Description
void	insert(String word)
boolean	search(String word)
boolean	search(String word, g0201_0300.s0208_implement_trie_prefix_tree.Trie.TrieNode root, int idx)
boolean	startsWith(String prefix)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

Trie

public Trie()

Method Details

insert

public void insert(String word)

search

public boolean search(String word)

search

public boolean search(String word,
 g0201_0300.s0208_implement_trie_prefix_tree.Trie.TrieNode root,
 int idx)

startsWith

public boolean startsWith(String prefix)