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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 * 104
calls in total will be made to insert
, search
, and startsWith
.class Trie:
def __init__(self):
"""
Initialize your data structure here.
"""
self.children = [None] * 26
self.is_end = False
def insert(self, word: str) -> None:
"""
Inserts a word into the trie.
"""
node = self
for c in word:
index = ord(c) - ord("a")
if node.children[index] is None:
node.children[index] = Trie()
node = node.children[index]
node.is_end = True
def search(self, word: str) -> bool:
"""
Returns if the word is in the trie.
"""
node = self._search_prefix(word)
return node is not None and node.is_end
def startsWith(self, prefix: str) -> bool:
"""
Returns if there is any word in the trie that starts with the given prefix.
"""
node = self._search_prefix(prefix)
return node is not None
def _search_prefix(self, prefix: str):
node = self
for c in prefix:
index = ord(c) - ord("a")
if node.children[index] is None:
return None
node = node.children[index]
return node
# Your Trie object will be instantiated and called as such:
# obj = Trie()
# obj.insert(word)
# param_2 = obj.search(word)
# param_3 = obj.startsWith(prefix)
class Trie {
private Trie[] children;
private boolean isEnd;
/** Initialize your data structure here. */
public Trie() {
children = new Trie[26];
isEnd = false;
}
/** Inserts a word into the trie. */
public void insert(String word) {
Trie node = this;
for (int i = 0; i < word.length(); ++i) {
char c = word.charAt(i);
int index = c - 'a';
if (node.children[index] == null) {
node.children[index] = new Trie();
}
node = node.children[index];
}
node.isEnd = true;
}
/** Returns if the word is in the trie. */
public boolean search(String word) {
Trie node = searchPrefix(word);
return node != null && node.isEnd;
}
/** Returns if there is any word in the trie that starts with the given prefix. */
public boolean startsWith(String prefix) {
Trie node = searchPrefix(prefix);
return node != null;
}
private Trie searchPrefix(String prefix) {
Trie node = this;
for (int i = 0; i < prefix.length(); ++i) {
char c = prefix.charAt(i);
int index = c - 'a';
if (node.children[index] == null) {
return null;
}
node = node.children[index];
}
return node;
}
}
/**
* Your Trie object will be instantiated and called as such:
* Trie obj = new Trie();
* obj.insert(word);
* boolean param_2 = obj.search(word);
* boolean param_3 = obj.startsWith(prefix);
*/
/**
* Initialize your data structure here.
*/
var Trie = function() {
this.children = {};
};
/**
* Inserts a word into the trie.
* @param {string} word
* @return {void}
*/
Trie.prototype.insert = function(word) {
let node = this.children;
for (let char of word) {
if (!node[char]) {
node[char] = {};
}
node = node[char];
}
node.isEnd = true;
};
/**
* Returns if the word is in the trie.
* @param {string} word
* @return {boolean}
*/
Trie.prototype.search = function(word) {
let node = this.searchPrefix(word);
return node != undefined && node.isEnd != undefined;
};
Trie.prototype.searchPrefix = function (prefix) {
let node = this.children;
for (let char of prefix) {
if (!node[char]) return false;
node = node[char];
}
return node;
}
/**
* Returns if there is any word in the trie that starts with the given prefix.
* @param {string} prefix
* @return {boolean}
*/
Trie.prototype.startsWith = function(prefix) {
return this.searchPrefix(prefix);
};
/**
* Your Trie object will be instantiated and called as such:
* var obj = new Trie()
* obj.insert(word)
* var param_2 = obj.search(word)
* var param_3 = obj.startsWith(prefix)
*/
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