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Commit a0e0fd8

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feat(trie): implement trie data structure
1 parent bbe69dd commit a0e0fd8

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3 files changed

+306
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lines changed

3 files changed

+306
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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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// 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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* 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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* @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) { return words; }
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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 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.spec.js

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const Trie = require('./trie');
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describe('Trie', () => {
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let trie;
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beforeEach(() => {
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trie = new Trie();
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});
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describe('construtor', () => {
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it('should initialize trie', () => {
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expect(trie).toBeDefined();
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});
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it('should set default value to undefined', () => {
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expect(trie.val).toEqual(undefined);
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});
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it('should initialization value', () => {
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trie = new Trie(1);
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expect(trie.val).toEqual(1);
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});
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it('should initialize children as empty map', () => {
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expect(trie.children).toEqual({});
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});
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it('should not be a word by default', () => {
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expect(trie.isWord).toEqual(false);
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});
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});
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describe('insert', () => {
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it('should insert a word', () => {
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trie.insert('ab');
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expect(trie.children.a).toBeDefined();
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expect(trie.children.a.children.b).toBeDefined();
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expect(trie.children.a.isWord).toEqual(false);
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expect(trie.children.a.children.b.isWord).toEqual(true);
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});
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it('should insert multiple words with the same root', () => {
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trie.insert('a');
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trie.insert('ab');
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expect(trie.children.a.isWord).toEqual(true);
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expect(trie.children.a.children.b.isWord).toEqual(true);
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});
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});
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describe('search & startsWith', () => {
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beforeEach(() => {
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trie.insert('dog');
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trie.insert('dogs');
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trie.insert('door');
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});
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it('should search for words', () => {
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expect(trie.search('dog')).toEqual(true);
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});
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it('should not match incomplete words by default', () => {
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expect(trie.search('do')).toEqual(false);
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});
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it('should match partial words if partial is set', () => {
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expect(trie.search('do', {
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partial: true,
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})).toEqual(true);
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expect(trie.startsWith('do')).toEqual(true);
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});
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it('should not match non existing words', () => {
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expect(trie.search('doors')).toEqual(false);
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});
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it('should not match non existing words with partials', () => {
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expect(trie.search('doors', {
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partial: true,
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})).toEqual(false);
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expect(trie.startsWith('doors')).toEqual(false);
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});
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});
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describe('when multiple words are inserted', () => {
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beforeEach(() => {
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trie.insert('dog');
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trie.insert('dogs');
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trie.insert('door');
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trie.insert('day');
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trie.insert('cat');
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});
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describe('getAllWords', () => {
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it('should get all words', () => {
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const words = trie.getAllWords();
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expect(words.length).toEqual(5);
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expect(words).toEqual(['dog', 'dogs', 'door', 'day', 'cat']);
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});
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it('should use prefix', () => {
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const words = trie.getAllWords("Adrian's ");
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expect(words.length).toEqual(5);
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expect(words).toEqual([
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"Adrian's dog",
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"Adrian's dogs",
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"Adrian's door",
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"Adrian's day",
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"Adrian's cat",
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]);
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});
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});
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describe('autocomplete', () => {
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it('should return all words if not prefix is given', () => {
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const words = trie.autocomplete();
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expect(words.length).toBe(5);
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expect(words).toEqual(['dog', 'dogs', 'door', 'day', 'cat']);
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});
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it('should auto complete words given a prefix', () => {
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const words = trie.autocomplete('do');
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expect(words.length).toBe(3);
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expect(words).toEqual(['dog', 'dogs', 'door']);
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});
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it('should handle non-existing words prefixes', () => {
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const words = trie.autocomplete('co');
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expect(words.length).toBe(0);
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expect(words).toEqual([]);
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});
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});
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});
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});

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