1+ # Design a data structure that supports adding new words and finding if a string matches
2+ # any previously added string.
3+ 4+ # Implement the WordDictionary class:
5+ 6+ # WordDictionary() Initializes the object.
7+ # void addWord(word) Adds word to the data structure, it can be matched later.
8+ # bool search(word) Returns true if there is any string in the data structure that matches
9+ # word or false otherwise. word may contain dots '.' where dots can be matched with any letter.
10+ 11+ 12+ # Example:
13+ # Input
14+ # ["WordDictionary","addWord","addWord","addWord","search","search","search","search"]
15+ # [[],["bad"],["dad"],["mad"],["pad"],["bad"],[".ad"],["b.."]]
16+ # Output
17+ # [null,null,null,null,false,true,true,true]
18+ 19+ # Explanation
20+ # WordDictionary wordDictionary = new WordDictionary();
21+ # wordDictionary.addWord("bad");
22+ # wordDictionary.addWord("dad");
23+ # wordDictionary.addWord("mad");
24+ # wordDictionary.search("pad"); // return False
25+ # wordDictionary.search("bad"); // return True
26+ # wordDictionary.search(".ad"); // return True
27+ # wordDictionary.search("b.."); // return True
28+ 29+ 30+ # Constraints:
31+ 32+ # 1 <= word.length <= 25
33+ # word in addWord consists of lowercase English letters.
34+ # word in search consist of '.' or lowercase English letters.
35+ # There will be at most 2 dots in word for search queries.
36+ # At most 104 calls will be made to addWord and search.
37+ 38+ 39+ class TrieNode :
40+ def __init__ (self ):
41+ self .children = {}
42+ self .isWord = False
43+ 44+ class WordDictionary :
45+ 46+ def __init__ (self ):
47+ self .root = TrieNode ()
48+ 49+ def addWord (self , word : str ) -> None :
50+ node = self .root
51+ for char in word :
52+ if char not in node .children :
53+ node .children [char ] = TrieNode ()
54+ node = node .children [char ]
55+ node .isWord = True
56+ 57+ def search (self , word : str ) -> bool :
58+ def find (node , i ):
59+ if i == len (word ):
60+ return node .isWord
61+ char = word [i ]
62+ if char == '.' :
63+ for child in node .children .values ():
64+ if find (child , i + 1 ):
65+ return True
66+ return False
67+ if char not in node .children :
68+ return False
69+ return find (node .children [char ], i + 1 )
70+ 71+ return find (self .root , 0 )
72+ 73+ 74+ # Your WordDictionary object will be instantiated and called as such:
75+ # obj = WordDictionary()
76+ # obj.addWord(word)
77+ # param_2 = obj.search(word)
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