This problem was asked by Twitter.
Implement an autocomplete system. That is, given a query string s and a set of all possible query strings, return all strings in the set that have s as a prefix.
For example, given the query string de and the set of strings [dog, deer, deal], return [deer, deal].
Hint: Try preprocessing the dictionary into a more efficient data structure to speed up queries.
经典用Trie树。
class TrieNode:
def __init__(self) -> None:
self.children ={}
self.is_end_of_word =False
class AutocompleteSystem:
def __init__(self, words) -> None:
self.root = TrieNode()
self.build_trie(words)
def build_trie(self, words):
for word in words:
node = self.root
for char in word:
if char not in node.children:
node.children[char] = TrieNode()
node = node.children[char]
node.is_end_of_word = True
def autocomplete(self, prefix):
node = self.root
result = []
for char in prefix:
if char not in node.children:
return result
node = node.children[char]
self.find_words_with_prefix(node, prefix, result)
return result
def find_words_with_prefix(self, node, current_word, result):
if node.is_end_of_word:
result.append(current_word)
for char, child_node in node.children.items():
self.find_words_with_prefix(child_node, current_word + char, result)
# Create an AutocompleteSystem with a set of words
autocomplete_system = AutocompleteSystem(["dog", "deer", "deal"])
# Query for autocomplete suggestions
result = autocomplete_system.autocomplete("de")
print(result) # Output: ['deer', 'deal']
