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.