README_CN.md

211. 添加与搜索单词 - 数据结构设计

如果数据结构中有任何与word匹配的字符串，则bool search（word）返回true，否则返回false。 单词可能包含点“.” 点可以与任何字母匹配的地方。

请你设计一个数据结构，支持 添加新单词 和 查找字符串是否与任何先前添加的字符串匹配 。

实现词典类 WordDictionary ：

• WordDictionary() 初始化词典对象
• void addWord(word) 将 word 添加到数据结构中，之后可以对它进行匹配
• bool search(word) 如果数据结构中存在字符串与 word 匹配，则返回 true ；否则，返回 false 。word 中可能包含一些 '.' ，每个 . 都可以表示任何一个字母。

示例:

输入:
["WordDictionary","addWord","addWord","addWord","search","search","search","search"]
[[],["bad"],["dad"],["mad"],["pad"],["bad"],[".ad"],["b.."]]
输出:
[null,null,null,null,false,true,true,true]
解释:
WordDictionary wordDictionary = new WordDictionary();
wordDictionary.addWord("bad");
wordDictionary.addWord("dad");
wordDictionary.addWord("mad");
wordDictionary.search("pad"); // return False
wordDictionary.search("bad"); // return True
wordDictionary.search(".ad"); // return True
wordDictionary.search("b.."); // return True

提示:

• 1 <= word.length <= 500
• addWord 中的 word 由小写英文字母组成
• search 中的 word 由 '.' 或小写英文字母组成
• 最调用多 50000 次 addWord 和 search

题解 (Python)

1. 题解

class WordDictionary:

    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.children = [None] * 26
        self.is_end = False

    def addWord(self, word: str) -> None:
        """
        Adds a word into the data structure.
        """
        i = ord(word[0]) - 97

        if not self.children[i]:
            self.children[i] = WordDictionary()

        if len(word) == 1:
            self.children[i].is_end = True
        else:
            self.children[i].addWord(word[1:])

    def search(self, word: str) -> bool:
        """
        Returns if the word is in the data structure. A word could contain the dot character '.' to represent any one letter.
        """
        i = ord(word[0]) - 97

        if word == '.':
            return any(child.is_end for child in self.children if child)
        elif len(word) == 1:
            return self.children[i] and self.children[i].is_end
        elif word[0] == '.':
            return any(child.search(word[1:]) for child in self.children if child)
        else:
            return self.children[i] and self.children[i].search(word[1:])


# Your WordDictionary object will be instantiated and called as such:
# obj = WordDictionary()
# obj.addWord(word)
# param_2 = obj.search(word)