Leetcode 208. Implement Trie (Prefix Tree)

Tyan

发布于 2021-07-14 13:53:06

1530

发布于 2021-07-14 13:53:06

文章被收录于专栏：SnailTyan

1. Description

2. Solution

**解析：**Version 1，字典树的实现，每一个结点都可能包含26个子节点，其子结点的key为a-z，除根节点外，每个结点还可能包含end作为单词结束的标志。

Version 1

class TrieNode:
    def __init__(self):
        self.children = {}


class Trie:

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


    def insert(self, word: str) -> None:
        """
        Inserts a word into the trie.
        """
        current = self.root
        for ch in word:
            if ch in current.children:
                current = current.children[ch]
            else:
                node = TrieNode()
                current.children[ch] = node
                current = node

        current.children['end'] = 'end'


    def search(self, word: str) -> bool:
        """
        Returns if the word is in the trie.
        """
        current = self.root
        for ch in word:
            if ch in current.children:
                current = current.children[ch]
            else:
                return False
        return 'end' in current.children:


    def startsWith(self, prefix: str) -> bool:
        """
        Returns if there is any word in the trie that starts with the given prefix.
        """
        current = self.root
        for ch in prefix:
            if ch in current.children:
                current = current.children[ch]
            else:
                return False
        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)