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.$3*10^4$
calls in total will be made to insert
, search
, and startsWith
.題目要我們實作一個可以儲存所有小寫英文字的一個 Trie結構
需要實作出以下 method: