字典树

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1 字典树（Trie）

2 实现方法

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class Trie:

    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.root = {}
        # 特殊标记
        self.word_end = -1



    def insert(self, word: str) -> None:
        """
        Inserts a word into the trie.
        """
        cur_node = self.root
        for char in word:
            if not char in cur_node:
                cur_node[char] = {}
            cur_node = cur_node[char]
        cur_node[self.word_end] = True
                

    def search(self, word: str) -> bool:
        """
        Returns if the word is in the trie.
        """
        cur_node = self.root
        for char in word:
            if char not in cur_node:
                return False
            cur_node = cur_node[char]
        
        if self.word_end not in cur_node:
            return False
        return True



    def startsWith(self, prefix: str) -> bool:
        """
        Returns if there is any word in the trie that starts with the given prefix.
        """
        cur_node = self.root
        for char in prefix:
            if not char in cur_node:
                return False
            cur_node = cur_node[char]
        
        return True

# 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)
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