leetcode 208. 实现 Trie (前缀树)

实现一个 Trie (前缀树)，包含 insert, search, 和 startsWith 这三个操作。

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示例:

Trie trie = new Trie();

trie.insert("apple");
trie.search("apple");   // 返回 true
trie.search("app");     // 返回 false
trie.startsWith("app"); // 返回 true
trie.insert("app");   
trie.search("app");     // 返回 true
说明:

你可以假设所有的输入都是由小写字母 a-z 构成的。
保证所有输入均为非空字符串。

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代码

class TrieNode(object):
    def __init__(self):
        self.children = defaultdict(TrieNode)
        self.isEnd = False


class Trie(object):

    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.root = TrieNode()


    def insert(self, word):
        """
        Inserts a word into the trie.
        :type word: str
        :rtype: None
        """
        node = self.root
        for c in word:
            node = node.children[c]
        node.isEnd = True

    def search(self, word):
        """
        Returns if the word is in the trie.
        :type word: str
        :rtype: bool
        """
        node = self.root
        for c in word:
            if c not in node.children:
                return False
            else:
                node = node.children[c]
        return node.isEnd

    def startsWith(self, prefix):
        """
        Returns if there is any word in the trie that starts with the given prefix.
        :type prefix: str
        :rtype: bool
        """
        node = self.root
        for c in prefix:
            if c not in node.children:
                return False
            else:
                node = node.children[c]
        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)

题解：https://leetcode-cn.com/problems/implement-trie-prefix-tree/solution/trie-tree-de-shi-xian-gua-he-chu-xue-zhe-by-huwt/