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| 1 | +/** |
| 2 | + * Class representing a Trie data structure. |
| 3 | + * @summary Add and Search Word - Data structure design {@link https://leetcode.com/problems/add-and-search-word-data-structure-design/} |
| 4 | + * @description Implement a structure that allows to add words and search words with wildcard support. |
| 5 | + */ |
| 6 | +class WordDictionary { |
| 7 | + /** |
| 8 | + * @description Create a new Trie with root node. |
| 9 | + */ |
| 10 | + constructor() { |
| 11 | + this.trie = {}; |
| 12 | + } |
| 13 | + |
| 14 | + /** |
| 15 | + * @description Add word to the trie (supported letters a-z). |
| 16 | + * @param {string} word String to be added to our trie. |
| 17 | + * Space O(n) - where n is word.length - at best we add 0 chars (word is already here), at worst word.length - when none of the leaves/branches exist. |
| 18 | + * Time O(n) - where n is word.length, iterate over string length. |
| 19 | + */ |
| 20 | + addWord(word) { |
| 21 | + let currentNode = this.trie; |
| 22 | + |
| 23 | + for (let index = 0; index < word.length; index++) { |
| 24 | + const char = word[index]; |
| 25 | + |
| 26 | + if (!currentNode[char]) currentNode[char] = {}; |
| 27 | + |
| 28 | + currentNode = currentNode[char]; |
| 29 | + } |
| 30 | + |
| 31 | + currentNode.hasWord = true; |
| 32 | + } |
| 33 | + |
| 34 | + /** |
| 35 | + * @description Search word in a trie (supported letters a-z and match all char '.'). |
| 36 | + * @param {string} word String to search for |
| 37 | + * @param {Object} [node=this.trie] Node currently at, defaults to trie root. |
| 38 | + * @param {number} index Position of current node relative to search term. |
| 39 | + * @return {boolean} true mmatching value found in trie. |
| 40 | + * Space(n) - for stack (recursion). |
| 41 | + * Time O(m*n) - for worst case scenario (all '.') we have to traverse all leaves(m) to word.length(n) depth. |
| 42 | + */ |
| 43 | + search(word, node = this.trie, index = 0) { |
| 44 | + const SPECIAL_CHAR = '.'; |
| 45 | + |
| 46 | + const char = word[index]; |
| 47 | + |
| 48 | + if (index === word.length - 1) { |
| 49 | + if (char === SPECIAL_CHAR) return Object.keys(node).some(key => node[key].hasWord); |
| 50 | + return !!node[char]?.hasWord; |
| 51 | + } |
| 52 | + |
| 53 | + if (char === SPECIAL_CHAR) return Object.keys(node).some(key => this.search(word, node[key], index + 1)); |
| 54 | + if (char !== SPECIAL_CHAR) { |
| 55 | + if (!node[char]) return false; |
| 56 | + else return this.search(word, node[char], index + 1); |
| 57 | + } |
| 58 | + } |
| 59 | +} |
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