// --- Directions// Given the root node of a tree, return// an array where each element is the width// of the tree at each level.// --- Example// Given://     0//   / |  \// 1   2   3// |       |// 4       5// Answer: [1, 3, 2]

 

function levelWidth(root) {  let counts = [0];  let levels = [root, "$end$"];  // [1, 3, 2]  // ["e"]  while (levels.length > 1) {    const current = levels.shift();    if (current === "$end$") {      counts[counts.length] = 0;      levels.push("$end$");    } else {      const { children } = current;      for (let node of children) {        levels.push(node);      }      counts[counts.length - 1]++;    }  }  return counts;}module.exports = levelWidth;

 

Test:

const Node = require('./node');const levelWidth = require('./index');test('levelWidth is a function', () => {  expect(typeof levelWidth).toEqual('function');});test('levelWidth returns number of nodes at widest point', () => {  const root = new Node(0);  root.add(1);  root.add(2);  root.add(3);  root.children[0].add(4);  root.children[2].add(5);  expect(levelWidth(root)).toEqual([1, 3, 2]);});test('levelWidth returns number of nodes at widest point', () => {  const root = new Node(0);  root.add(1);  root.children[0].add(2);  root.children[0].add(3);  root.children[0].children[0].add(4);  expect(levelWidth(root)).toEqual([1, 1, 2, 1]);});