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).

Medium

A trie (pronounced as “try”) or prefix tree 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.

Implement the Trie class:

  • Trie() Initializes the trie object.
  • void insert(String word) Inserts the string word into the trie.
  • boolean search(String word) Returns true if the string word is in the trie (i.e., was inserted before), and false otherwise.
  • boolean startsWith(String prefix) Returns true if there is a previously inserted string word that has the prefix prefix, and false otherwise.

Example 1:

Input

 ["Trie", "insert", "search", "search", "startsWith", "insert", "search"]
 [ [], ["apple"], ["apple"], ["app"], ["app"], ["app"], ["app"]]

Output: [null, null, true, false, true, null, true]

Explanation:

 Trie trie = new Trie();
 trie.insert("apple"); trie.search("apple"); // return True
 trie.search("app"); // return False
 trie.startsWith("app"); // return True
 trie.insert("app");
 trie.search("app"); // return True

Constraints:

  • 1 <= word.length, prefix.length <= 2000
  • word and prefix consist only of lowercase English letters.
  • At most 3 * 104 calls in total will be made to insert, search, and startsWith.

  • Constructor Details

    • Trie

      public Trie()

  • Method Details

    • insert

      public void insert(String word)

    • search

      public boolean search(String word)

    • startsWith

      public boolean startsWith(String prefix)