211. Design Add and Search Words Data Structure

https://leetcode.com/problems/design-add-and-search-words-data-structure/

solution

class TrieNode:
    def __init__(self):
        self.data = {}
        self.is_word = False

class WordDictionary:
    def __init__(self):
        self.root = TrieNode()

    def addWord(self, word: str) -> None:
        cur = self.root
        for char in word:
            cur = cur.data.setdefault(char, TrieNode())
        cur.is_word = True

    def search(self, word: str) -> bool:
        return self.dfs(self.root, 0, word)

    def dfs(self, node, index, word):  # 按字母从trie中获取
        if index == len(word):
            return node.is_word

        if word[index] == '.':  # 通配符的搜索
            for child in node.data.values():
                if self.dfs(child, index + 1, word):
                    return True

        if word[index] in node.data:  # 非通配符
            return self.dfs(node.data[word[index]], index+1, word)
        return False

时间复杂度：O() 空间复杂度：O()

follow up

676. Implement Magic Dictionary

720. Longest Word in Dictionary

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

class Trie(object):
    def __init__(self):
        self.root=TrieNode()

    def insert(self, word):
        node=self.root
        for c in word:
            node =node.children[c]
        node.isEnd=True
        node.word=word

    def bfs(self):
        q = collections.deque([self.root])
        res = ''
        while q:
            cur = q.popleft()
            for n in cur.children.values():
                if n.isEnd:
                    q.append(n)
                    if len(n.word) > len(res) or n.word < res:
                        res = n.word
        return res

class Solution(object):
    def longestWord(self, words):
        trie = Trie()
        for w in words:
            trie.insert(w)
        return trie.bfs()