[模板题] - 208. 实现 Trie (前缀树)

题目链接	208. 实现 Trie (前缀树)
思路	模板题 - Trie树
题解链接	官方题解
关键点	无
时间复杂度	\(O(\sum_{i}\#\text{word}_{i})\)
空间复杂度	\(O(\sum_{i}\#\text{word}_{i})\)

代码实现：

class Trie:
    def __init__(self):
        self.children = [None] * 26
        self.isEnd = False
    
    def insert(self, word: str) -> None:
        node = self
        for ch in word:
            ch = ord(ch) - ord('a')
            if not node.children[ch]:
                node.children[ch] = Trie()
            node = node.children[ch]
        node.isEnd = True
    
    def search(self, word: str) -> bool:
        node = self._searchPrefix(word)
        return node is not None and node.isEnd
    
    def startsWith(self, prefix: str) -> bool:
        return self._searchPrefix(prefix) is not None
    
    def _searchPrefix(self, prefix) -> "Trie":
        node = self
        for ch in prefix:
            ch = ord(ch) - ord('a')
            if not node.children[ch]:
                return None
            node = node.children[ch]
        return node