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Commit 965fbd1

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Merge pull request #43 from amejiarosario/feature/trie
feat(trie): implement trie data structure
2 parents 567c110 + e31cc62 commit 965fbd1

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5 files changed

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lines changed

5 files changed

+579
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lines changed

‎src/data-structures/trees/trie-1.js

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class Trie {
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constructor(val) {
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this.val = val;
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this.children = {};
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this.isWord = false;
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}
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/**
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* Insert word into trie and mark last element as such.
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* @param {string} word
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* @return {undefined}
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*/
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insert(word) {
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let curr = this;
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for (const char of word) {
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curr.children[char] = curr.children[char] || new Trie(char);
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curr = curr.children[char];
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}
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curr.isWord = true;
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}
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/**
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* Search for complete word (by default) or partial if flag is set.
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* @param {string} word - Word to search.
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* @param {boolean} options.partial - Whether or not match partial matches.
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* @return {boolean}
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*/
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search(word, { partial } = {}) {
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let curr = this;
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for (const char of word) {
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if (!curr.children[char]) { return false; }
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curr = curr.children[char];
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}
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return partial ? true : curr.isWord;
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}
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/**
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* Return true if any word on the trie starts with the given prefix
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* @param {string} prefix - Partial word to search.
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* @return {boolean}
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*/
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startsWith(prefix) {
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return this.search(prefix, { partial: true });
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}
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/**
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* Returns all the words from the current `node`.
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* Uses backtracking.
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*
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* @param {string} prefix - The prefix to append to each word.
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* @param {string} node - Current node to start backtracking.
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* @param {string[]} words - Accumulated words.
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* @param {string} string - Current string.
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*/
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getAllWords(prefix = '', node = this, words = [], string = '') {
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if (node.isWord) {
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words.push(`${prefix}${string}`);
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}
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for (const char of Object.keys(node.children)) {
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this.getAllWords(prefix, node.children[char], words, `${string}${char}`);
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}
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return words;
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}
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/**
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* Return true if found the word to be removed, otherwise false.
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* Iterative approach
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* @param {string} word - The word to remove
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* @returns {boolean}
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*/
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remove(word) {
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const stack = [];
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let curr = this;
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for (const char of word) {
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if (!curr.children[char]) { return false; }
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stack.push(curr);
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curr = curr.children[char];
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}
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if (!curr.isWord) { return false; }
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let node = stack.pop();
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do {
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node.children = {};
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node = stack.pop();
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} while (node && !node.isWord);
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return true;
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}
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/**
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* Return true if found the word to be removed, otherwise false.
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* recursive approach
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* @param {string} word - The word to remove
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* @returns {boolean}
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*/
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remove2(word, i = 0, parent = this) {
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if (i === word.length - 1) {
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return true;
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}
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const child = parent.children[word.charAt(i)];
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if (!child) return false;
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const found = this.remove(word, i + 1, child);
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if (found) {
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delete parent.children[word.charAt(i)];
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}
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return true;
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}
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}
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// Aliases
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Trie.prototype.add = Trie.prototype.insert;
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module.exports = Trie;

‎src/data-structures/trees/trie-2.js

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class Trie {
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constructor(val) {
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this.val = val;
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this.children = {};
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this.isWord = false;
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}
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/**
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* Insert word into trie and mark last element as such.
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* @param {string} word
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* @return {undefined}
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*/
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insert(word) {
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let curr = this;
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for (const char of word) {
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curr.children[char] = curr.children[char] || new Trie(char);
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curr = curr.children[char];
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}
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curr.isWord = true;
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}
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/**
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* Return true if found the word to be removed, otherwise false.
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* @param {string} word - The word to remove
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* @returns {boolean}
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*/
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remove(word) {
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return this.removeHelper(word);
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}
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/**
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* Remove word from trie, return true if found, otherwise false.
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* @param {string} word - The word to remove.
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* @param {Trie} parent - The parent node.
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* @param {number} index - The index.
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* @param {number} meta.stop - Keeps track of the last letter that won't be removed.
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* @returns {boolean}
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*/
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removeHelper(word, parent = this, index = 0, meta = { stop: 0 }) {
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if (index === word.length) {
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parent.isWord = false;
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if (Object.keys(parent.children)) { meta.stop = index; }
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return true;
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}
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const child = parent.children[word.charAt(index)];
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if (!child) { return false; }
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if (parent.isWord) { meta.stop = index; }
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const found = this.removeHelper(word, child, index + 1, meta);
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// deletes all the nodes beyond `meta.stop`.
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if (found && index >= meta.stop) {
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delete parent.children[word.charAt(index)];
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}
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return found;
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}
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/**
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* Retun last node that matches word or prefix or false if not found.
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* @param {string} word - Word to search.
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* @param {boolean} options.partial - Whether or not match partial matches.
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* @return {Trie|false}
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*/
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searchNode(word) {
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let curr = this;
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for (const char of word) {
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if (!curr.children[char]) { return false; }
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curr = curr.children[char];
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}
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return curr;
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}
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/**
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* Search for complete word (by default) or partial if flag is set.
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* @param {string} word - Word to search.
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* @param {boolean} options.partial - Whether or not match partial matches.
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* @return {boolean}
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*/
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search(word, { partial } = {}) {
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const curr = this.searchNode(word);
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if (!curr) { return false; }
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return partial ? true : curr.isWord;
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}
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/**
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* Return true if any word on the trie starts with the given prefix
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* @param {string} prefix - Partial word to search.
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* @return {boolean}
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*/
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startsWith(prefix) {
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return this.search(prefix, { partial: true });
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}
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/**
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* Returns all the words from the current `node`.
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* Uses backtracking.
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*
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* @param {string} prefix - The prefix to append to each word.
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* @param {string} node - Current node to start backtracking.
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*/
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getAllWords(prefix = '', node = this) {
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let words = [];
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if (!node) { return words; }
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if (node.isWord) {
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words.push(prefix);
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}
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for (const char of Object.keys(node.children)) {
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const newWords = this.getAllWords(`${prefix}${char}`, node.children[char]);
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words = words.concat(newWords);
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}
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return words;
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}
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/**
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* Return a list of words matching the prefix
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* @param {*} prefix - The prefix to match.
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* @returns {string[]}
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*/
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autocomplete(prefix = '') {
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const curr = this.searchNode(prefix);
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return this.getAllWords(prefix, curr);
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}
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}
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// Aliases
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Trie.prototype.add = Trie.prototype.insert;
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module.exports = Trie;

‎src/data-structures/trees/trie.js

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class Trie {
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constructor(val) {
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this.val = val;
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this.children = {};
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this.isWord = false;
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}
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/**
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* Insert word into trie and mark last element as such.
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* @param {string} word
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* @return {undefined}
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*/
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insert(word) {
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let curr = this;
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for (const char of word) {
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curr.children[char] = curr.children[char] || new Trie(char);
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curr = curr.children[char];
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}
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curr.isWord = true;
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}
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/**
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* Return true if found the word to be removed, otherwise false.
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* @param {string} word - The word to remove
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* @returns {boolean}
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*/
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remove(word) {
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let curr = this;
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// let lastWordToKeep = 0;
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const stack = [curr];
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// find word and stack path
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for (const char of word) {
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if (!curr.children[char]) { return false; }
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// lastWordToKeep += 1;
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curr = curr.children[char];
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stack.push(curr);
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}
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let child = stack.pop();
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child.isWord = false;
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// remove non words without children
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while (stack.length) {
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const parent = stack.pop();
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if (!child.isWord && !Object.keys(child.children).length) {
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delete parent.children[child.val];
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}
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child = parent;
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}
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return true;
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}
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/**
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* Retun last node that matches word or prefix or false if not found.
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* @param {string} word - Word to search.
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* @param {boolean} options.partial - Whether or not match partial matches.
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* @return {Trie|false}
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*/
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searchNode(word) {
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let curr = this;
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for (const char of word) {
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if (!curr.children[char]) { return false; }
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curr = curr.children[char];
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}
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return curr;
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}
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/**
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* Search for complete word (by default) or partial if flag is set.
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* @param {string} word - Word to search.
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* @param {boolean} options.partial - Whether or not match partial matches.
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* @return {boolean}
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*/
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search(word, { partial } = {}) {
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const curr = this.searchNode(word);
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if (!curr) { return false; }
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return partial ? true : curr.isWord;
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}
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/**
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* Return true if any word on the trie starts with the given prefix
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* @param {string} prefix - Partial word to search.
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* @return {boolean}
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*/
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startsWith(prefix) {
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return this.search(prefix, { partial: true });
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}
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/**
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* Returns all the words from the current `node`.
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* Uses backtracking.
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*
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* @param {string} prefix - The prefix to append to each word.
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* @param {string} node - Current node to start backtracking.
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*/
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getAllWords(prefix = '', node = this) {
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let words = [];
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if (!node) { return words; }
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if (node.isWord) {
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words.push(prefix);
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}
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for (const char of Object.keys(node.children)) {
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const newWords = this.getAllWords(`${prefix}${char}`, node.children[char]);
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words = words.concat(newWords);
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}
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return words;
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}
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/**
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* Return a list of words matching the prefix
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* @param {*} prefix - The prefix to match.
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* @returns {string[]}
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*/
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autocomplete(prefix = '') {
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const curr = this.searchNode(prefix);
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return this.getAllWords(prefix, curr);
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}
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}
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// Aliases
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Trie.prototype.add = Trie.prototype.insert;
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module.exports = Trie;

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