Design Add and Search Words Data Structure
Problem
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)
Addsword
to the data structure, it can be matched later.bool search(word)
Returnstrue
if there is any string in the data structure that matchesword
orfalse
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
inaddWord
consists lower-case English letters.word
insearch
consist of'.'
or lower-case English letters.- At most
50000
calls will be made toaddWord
andsearch
.
Solution
class Node {
constructor() {
this.end = false;
this.children = {};
}
}
class WordDictionary {
constructor() {
this.root = new Node();
}
addWord(word) {
let r = this.root;
for (const c of word) {
if (!(c in r.children)) {
r.children[c] = new Node();
}
r = r.children[c];
}
r.end = true;
}
search(word, r = this.root, index = 0) {
if (word.length === index) {
return r.end;
}
const c = word[index];
if (c === ".") {
for (const key in r.children) {
if (this.search(word, r.children[key], index + 1)) {
return true;
}
}
} else if (c in r.children) {
return this.search(word, r.children[c], index + 1);
}
return false;
}
}
/**
* Your WordDictionary object will be instantiated and called as such:
* var obj = new WordDictionary()
* obj.addWord(word)
* var param_2 = obj.search(word)
*/
We will use a trie as our main data structure, and use DFS to find matching words.