const getSubsets = arr => arr.reduce((prev, curr) => prev.concat(prev.map(k => k.concat(curr))), [[]]);

// Examples
getSubsets([1, 2]);     // [[], [1], [2], [1, 2]]
getSubsets([1, 2, 3]);  // [[], [1], [2], [1, 2], [3], [1, 3], [2, 3], [1, 2, 3]]

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); // 1
kNearestNeighbors(data, labels, [1, 0], 2); // 0

const express = require('express')
const app = express()
const port = 3000

app.get('/', (req, res) => {
  res.send('Hello World!')
})

app.listen(port, () => {
  console.log(`Example app listening on port ${port}`)
})

const flat = arr => [].concat.apply([], arr.map(a => Array.isArray(a) ? flat(a) : a));
// Or
const flat = arr => arr.reduce((a, b) => Array.isArray(b) ? [...a, ...flat(b)] : [...a, b], []);

// Or
// See the browser compatibility at https://caniuse.com/#feat=array-flat
const flat = arr => arr.flat();

// Example
flat(['cat', ['lion', 'tiger']]);   // ['cat', 'lion', 'tiger']

//JavaScript program to swap two variables

//take input from the users
let a = prompt('Enter the first variable: ');
let b = prompt('Enter the second variable: ');

// XOR operator
a = a ^ b
b = a ^ b
a = a ^ b

console.log(`The value of a after swapping: ${a}`);
console.log(`The value of b after swapping: ${b}`);

//Use at https://mee6.xyz/leaderboard/732262089447702588
//Higher the spammy stat, the more spammy that person is.
//This is because mee doesn't give experience to people who post more comments in a minute.
function statBlock(title, value){
	let elm = document.createElement("div");
	elm.className = "leaderboardPlayerStatBlock";
	let titleElm = document.createElement("div");
	titleElm.className = "leaderboardPlayerStatName";
	titleElm.textContent = title;
	let valueElm = document.createElement("div");
	valueElm.className = "leaderboardPlayerStatValue";
	valueElm.textContent = value;
	elm.appendChild(titleElm);
	elm.appendChild(valueElm);
	elm.remove = function(){
	this.parentElement.removeChild(this);
	}
	return elm;
}
for(let player of Array.from(document.getElementsByClassName("leaderboardPlayer"))){
	if(player.spamminess) player.spamminess.remove();
	let messages = null;
	let experience = null;
	const statBlockArray = Array.from(player.querySelectorAll(".leaderboardPlayerStatBlock"));
	for(let statBlock of statBlockArray){
	const statName = statBlock.querySelector(".leaderboardPlayerStatName").textContent;
	const text = statBlock.querySelector(".leaderboardPlayerStatValue").textContent;
	const number = ((text.includes("k"))? (text.replace("k","") * 1000.0) : +(text));
	if(statName.includes("MESSAGES")){
	messages = number;
	}else if(statName.includes("EXPERIENCE")){
	experience = number;
	}
	}
	const stats = player.querySelector(".leaderboardPlayerStats");
	const messagesElement = stats.firstChild;

	const spamminess = ((messages/experience)*2000.0).toFixed(2);
	
	player.spamminess = stats.insertBefore(statBlock("SPAMMINESS", spamminess), messagesElement);
}