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Commit e31cc62

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feat(trie): feature complete
1 parent a81f6e1 commit e31cc62

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4 files changed

+159
-24
lines changed

4 files changed

+159
-24
lines changed

‎src/data-structures/trees/trie-2.js

Lines changed: 133 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,133 @@
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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; }
107+
if (node.isWord) {
108+
words.push(prefix);
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}
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for (const char of Object.keys(node.children)) {
112+
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

Lines changed: 22 additions & 23 deletions
Original file line numberDiff line numberDiff line change
@@ -27,32 +27,31 @@ class Trie {
2727
* @returns {boolean}
2828
*/
2929
remove(word) {
30-
return this.removeHelper(word);
31-
}
30+
let curr = this;
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// let lastWordToKeep = 0;
32+
const stack = [curr];
3233

33-
/**
34-
* Remove word from trie, return true if found, otherwise false.
35-
* @param {string} word - The word to remove.
36-
* @param {Trie} parent - The parent node.
37-
* @param {number} index - The index.
38-
* @param {number} meta.stop - Keeps track of the last letter that won't be removed.
39-
* @returns {boolean}
40-
*/
41-
removeHelper(word, parent = this, index = 0, meta = { stop: 0 }) {
42-
if (index === word.length) {
43-
parent.isWord = false;
44-
if (Object.keys(parent.children)) { meta.stop = index; }
45-
return true;
34+
// find word and stack path
35+
for (const char of word) {
36+
if (!curr.children[char]) { return false; }
37+
// lastWordToKeep += 1;
38+
curr = curr.children[char];
39+
stack.push(curr);
4640
}
47-
const child = parent.children[word.charAt(index)];
48-
if (!child) { return false; }
49-
if (parent.isWord) { meta.stop = index; }
50-
const found = this.removeHelper(word, child, index + 1, meta);
51-
// deletes all the nodes beyond `meta.stop`.
52-
if (found && index >= meta.stop) {
53-
delete parent.children[word.charAt(index)];
41+
42+
let child = stack.pop();
43+
child.isWord = false;
44+
45+
// remove non words without children
46+
while (stack.length) {
47+
const parent = stack.pop();
48+
if (!child.isWord && !Object.keys(child.children).length) {
49+
delete parent.children[child.val];
50+
}
51+
child = parent;
5452
}
55-
return found;
53+
54+
return true;
5655
}
5756

5857
/**

‎src/data-structures/trees/trie.spec.js

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -137,7 +137,7 @@ describe('Trie', () => {
137137
});
138138
});
139139

140-
describe('remove', () => {
140+
fdescribe('remove', () => {
141141
it('should remove a word', () => {
142142
trie = new Trie();
143143
trie.insert('a');

‎src/index.js

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -14,6 +14,8 @@ const BinaryTreeNode = require('./data-structures/trees/binary-tree-node');
1414
const AvlTree = require('./data-structures/trees/avl-tree');
1515
const RedBlackTree = require('./data-structures/trees/red-black-tree');
1616
const LRUCache = require('./data-structures/custom/lru-cache');
17+
const Trie = require('./data-structures/trees/trie');
18+
1719
// algorithms
1820
const bubbleSort = require('./algorithms/sorting/bubble-sort');
1921
const insertionSort = require('./algorithms/sorting/insertion-sort');
@@ -37,6 +39,7 @@ module.exports = {
3739
AvlTree,
3840
RedBlackTree,
3941
LRUCache,
42+
Trie,
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bubbleSort,
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insertionSort,
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selectionSort,

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