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const geometricProgression = (end, start = 1, step = 2) =>Array.from({length: Math.floor(Math.log(end / start) / Math.log(step)) + 1,}).map((_, i) => start * step ** i);geometricProgression(256); // [1, 2, 4, 8, 16, 32, 64, 128, 256]geometricProgression(256, 3); // [3, 6, 12, 24, 48, 96, 192]geometricProgression(256, 1, 4); // [1, 4, 16, 64, 256]
require("dotenv").config();const mongoose = require("mongoose");const db = process.env.MONGO_URI;const connectDB = async () => {try {await mongoose.connect(db, {useNewUrlParser: true,useUnifiedTopology: true,useFindAndModify: false,useCreateIndex: true});console.log("MongoDB Connected");} catch (err) {console.error(err.message);}};module.exports = connectDB;
function sortNumbers(arr) {return arr.slice().sort((a, b) => a - b);}const unsortedArray = [4, 1, 9, 6, 3, 5];const sortedArray = sortNumbers(unsortedArray);console.log("Unsorted Numbers:", unsortedArray);console.log("\n");console.log("Sorted Numbers:", sortedArray);
const kNearestNeighbors = (data, labels, point, k = 3) => {const kNearest = data.map((el, i) => ({dist: Math.hypot(...Object.keys(el).map(key => point[key] - el[key])),label: labels[i]})).sort((a, b) => a.dist - b.dist).slice(0, k);return kNearest.reduce((acc, { label }, i) => {acc.classCounts[label] =Object.keys(acc.classCounts).indexOf(label) !== -1? acc.classCounts[label] + 1: 1;if (acc.classCounts[label] > acc.topClassCount) {acc.topClassCount = acc.classCounts[label];acc.topClass = label;}return acc;},{classCounts: {},topClass: kNearest[0].label,topClassCount: 0}).topClass;};const data = [[0, 0], [0, 1], [1, 3], [2, 0]];const labels = [0, 1, 1, 0];kNearestNeighbors(data, labels, [1, 2], 2); // 1kNearestNeighbors(data, labels, [1, 0], 2); // 0
// Vanilla JS Solution:var app = document.getElementById('app');var typewriter = new Typewriter(app, { loop: true });typewriter.typeString("I'm John and I'm a super cool web developer").pauseFor(3000).deleteChars(13) // "web developer" = 13 characters.typeString("person to talk with!") // Will display "I'm John and I'm a super cool person to talk with!".start();// React Solution:import Typewriter from 'typewriter-effect';<Typewriteroptions={{ loop: true }}onInit={typewriter => {typewriter.typeString("I'm John and I'm a super cool web developer").pauseFor(3000).deleteChars(13) // "web developer" = 13 characters.typeString("person to talk with!") // Will display "I'm John and I'm a super cool person to talk with!".start();}}/>
class DoublyLinkedList {constructor() {this.nodes = [];}get size() {return this.nodes.length;}get head() {return this.size ? this.nodes[0] : null;}get tail() {return this.size ? this.nodes[this.size - 1] : null;}insertAt(index, value) {const previousNode = this.nodes[index - 1] || null;const nextNode = this.nodes[index] || null;const node = { value, next: nextNode, previous: previousNode };if (previousNode) previousNode.next = node;if (nextNode) nextNode.previous = node;this.nodes.splice(index, 0, node);}insertFirst(value) {this.insertAt(0, value);}insertLast(value) {this.insertAt(this.size, value);}getAt(index) {return this.nodes[index];}removeAt(index) {const previousNode = this.nodes[index - 1] || null;const nextNode = this.nodes[index + 1] || null;if (previousNode) previousNode.next = nextNode;if (nextNode) nextNode.previous = previousNode;return this.nodes.splice(index, 1);}clear() {this.nodes = [];}reverse() {this.nodes = this.nodes.reduce((acc, { value }) => {const nextNode = acc[0] || null;const node = { value, next: nextNode, previous: null };if (nextNode) nextNode.previous = node;return [node, ...acc];}, []);}*[Symbol.iterator]() {yield* this.nodes;}}const list = new DoublyLinkedList();list.insertFirst(1);list.insertFirst(2);list.insertFirst(3);list.insertLast(4);list.insertAt(3, 5);list.size; // 5list.head.value; // 3list.head.next.value; // 2list.tail.value; // 4list.tail.previous.value; // 5[...list.map(e => e.value)]; // [3, 2, 1, 5, 4]list.removeAt(1); // 2list.getAt(1).value; // 1list.head.next.value; // 1[...list.map(e => e.value)]; // [3, 1, 5, 4]list.reverse();[...list.map(e => e.value)]; // [4, 5, 1, 3]list.clear();list.size; // 0