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Trie Added in JS (#296)
* Trie Added in JS * Standard Fixed * updating DIRECTORY.md Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
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* [StackES6](https://github.com/TheAlgorithms/Javascript/blob/master/Data-Structures/Stack/StackES6.js)
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* [StackES6](https://github.com/TheAlgorithms/Javascript/blob/master/Data-Structures/Stack/StackES6.js)
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* Tree
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* Tree
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* [BinarySearchTree](https://github.com/TheAlgorithms/Javascript/blob/master/Data-Structures/Tree/BinarySearchTree.js)
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* [BinarySearchTree](https://github.com/TheAlgorithms/Javascript/blob/master/Data-Structures/Tree/BinarySearchTree.js)
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* [Trie](https://github.com/TheAlgorithms/Javascript/blob/master/Data-Structures/Tree/Trie.js)
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## Dynamic-Programming
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## Dynamic-Programming
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* [CoinChange](https://github.com/TheAlgorithms/Javascript/blob/master/Dynamic-Programming/CoinChange.js)
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* [CoinChange](https://github.com/TheAlgorithms/Javascript/blob/master/Dynamic-Programming/CoinChange.js)
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137
Data-Structures/Tree/Trie.js
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137
Data-Structures/Tree/Trie.js
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var TrieNode = function TrieNode (key, parent) {
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this.key = key
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this.count = 0
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this.children = Object.create(null)
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if (parent === undefined) {
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this.parent = null
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} else {
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this.parent = parent
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}
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}
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function Trie () {
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// create only root with null key and parent
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this.root = new TrieNode(null, null)
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}
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// Recursively finds the occurence of all words in a given node
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Trie.findAllWords = function (root, word, output) {
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if (root === null) return
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if (root.count > 0) {
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if (typeof output === 'object') { output.push({ word: word, count: root.count }) }
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}
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var key
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for (key in root.children) {
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word += key
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this.findAllWords(root.children[key], word, output)
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word = word.slice(0, -1)
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}
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}
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Trie.prototype.insert = function (word) {
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if (typeof word !== 'string') return
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if (word === '') {
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this.root.count += 1
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return
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}
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var node = this.root
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var len = word.length
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var i
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for (i = 0; i < len; i++) {
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if (node.children[word.charAt(i)] === undefined) { node.children[word.charAt(i)] = new TrieNode(word.charAt(i), node) }
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node = node.children[word.charAt(i)]
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}
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node.count += 1
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}
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Trie.prototype.findPrefix = function (word) {
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if (typeof word !== 'string') return null
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var node = this.root
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var len = word.length
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var i
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// After end of this loop node will be at desired prefix
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for (i = 0; i < len; i++) {
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if (node.children[word.charAt(i)] === undefined) return null // No such prefix exists
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node = node.children[word.charAt(i)]
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}
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return node
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}
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Trie.prototype.remove = function (word, count) {
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if (typeof word !== 'string') return
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if (typeof count !== 'number') count = 1
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else if (count <= 0) return
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// for empty string just delete count of root
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if (word === '') {
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if (this.root.count >= count) this.root.count -= count
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else this.root.count = 0
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return
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}
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var child = this.root
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var len = word.length
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var i, key
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// child: node which is to be deleted
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for (i = 0; i < len; i++) {
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key = word.charAt(i)
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if (child.children[key] === undefined) return
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child = child.children[key]
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}
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// Delete no of occurences specified
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if (child.count >= count) child.count -= count
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else child.count = 0
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// If some occurences are left we dont delete it or else
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// if the object forms some other objects prefix we dont delete it
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// For checking an empty object
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// https://stackoverflow.com/questions/679915/how-do-i-test-for-an-empty-javascript-object
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if (child.count <= 0 && (Object.keys(child.children).length && child.childre.constructor === Object)) {
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child.parent.children[child.key] = undefined
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}
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}
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Trie.prototype.findAllWords = function (prefix) {
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var output = []
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// find the node with provided prefix
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var node = this.findPrefix(prefix)
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// No such prefix exists
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if (node === null) return output
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Trie.findAllWords(node, prefix, output)
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return output
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}
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Trie.prototype.contains = function (word) {
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// find the node with given prefix
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var node = this.findPrefix(word)
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// No such word exists
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if (node === null || node.count === 0) return false
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return true
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}
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Trie.prototype.findOccurences = function (word) {
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// find the node with given prefix
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var node = this.findPrefix(word)
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// No such word exists
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if (node === null) return 0
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return node.count
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};
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// To test
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(function demo () {
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var x = new Trie()
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x.insert('sheldon')
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x.insert('hello')
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x.insert('anyword')
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x.insert('sheldoncooper')
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console.log(x.findOccurences('sheldon'))
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x.remove('anything')
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x.insert('sheldon')
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console.log(x.findOccurences('sheldon'))
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console.log(x.findAllWords('sheldon'))
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x.insert('anything')
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x.remove('sheldoncooper')
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console.log(x.contains('sheldoncooper'))
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console.log(x.findAllWords('sheldon'))
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})()
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