0211: Design Add and Search Words Data Structure

Problem Statement

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 <= 25
  • word in addWord consists of lowercase English letters.
  • word in search consist of '.' or lowercase English letters.
  • There will be at most 2 dots in word for search queries.
  • At most 104 calls will be made to addWord and search.

Code Solution

class TrieNode:
    def __init__(self, val):
        self.val = val
        self.end = False
        self.children = {}

class WordDictionary:
    def __init__(self):
        self.root = TrieNode('')
    
    def addWord(self, word):
        temp = self.root
        for cx, c in enumerate(word):
            if c not in temp.children:
                temp.children[c] = TrieNode(c)
            temp = temp.children[c]
        temp.end = True
        
    def search(self, word):
        def rec_search(wx, word, init_node):
            wlen = len(word)
            temp = init_node
            for cx in range(wx, wlen):
                c = word[cx]
                if c == '.':
                    flag = False
                    for cc in temp.children:
                        flag = flag or rec_search(1 + cx, word, temp.children[cc])
                    return flag
                if c not in temp.children:
                    return False
                temp = temp.children[c]
            return temp.end
        return rec_search(0, word, self.root)