Design Add and Search Words Data Structure - LeetCode
Design a data structure that supports adding new words and finding if a string matches any previously added string. Implement the WordDictionary class:
WordDictionary() Initializes the object. void addWord(word) Adds word to the data structure, it can be matched later. bool search(word) Returns true if there is any string in the data structure that matches word or false
otherwise. word may contain dots ‘.’ where dots can be matched with any letter.
Example: Input [“WordDictionary”,“addWord”,“addWord”,“addWord”,“search”,“search”,“search”,“search”] [[],[“bad”],[“dad”],[“mad”],[“pad”],[“bad”],[".ad"],[“b.."]] Output [null,null,null,null,false,true,true,true] Explanation 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
Constraints:
1 <= word.length <= 500
word in addWord consists lower-case English letters.
word in search consist of '.' or lower-case English letters.
At most 50000 calls will be made to addWord and search.
- code
class WordDictionary:
def __init__(self):
self.dic = {}
def addWord(self, word: str) -> None:
d = self.dic
for c in word:
if c not in d:
d[c] = {}
d = d[c]
d['$'] = True
def search(self, word: str) -> bool:
def helper(word, d):
for i, c in enumerate(word):
if c in d: d = d[c]
elif c != ".": return False
else: ## "."
for nex in d:
if nex != '$' and helper(word[i + 1:], d[nex]): return True
return False
return '$' in d
return helper(word, self.dic)