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class Graph {constructor(directed = true) {this.directed = directed;this.nodes = [];this.edges = new Map();}addNode(key, value = key) {this.nodes.push({ key, value });}addEdge(a, b, weight) {this.edges.set(JSON.stringify([a, b]), { a, b, weight });if (!this.directed)this.edges.set(JSON.stringify([b, a]), { a: b, b: a, weight });}removeNode(key) {this.nodes = this.nodes.filter(n => n.key !== key);[...this.edges.values()].forEach(({ a, b }) => {if (a === key || b === key) this.edges.delete(JSON.stringify([a, b]));});}removeEdge(a, b) {this.edges.delete(JSON.stringify([a, b]));if (!this.directed) this.edges.delete(JSON.stringify([b, a]));}findNode(key) {return this.nodes.find(x => x.key === key);}hasEdge(a, b) {return this.edges.has(JSON.stringify([a, b]));}setEdgeWeight(a, b, weight) {this.edges.set(JSON.stringify([a, b]), { a, b, weight });if (!this.directed)this.edges.set(JSON.stringify([b, a]), { a: b, b: a, weight });}getEdgeWeight(a, b) {return this.edges.get(JSON.stringify([a, b])).weight;}adjacent(key) {return [...this.edges.values()].reduce((acc, { a, b }) => {if (a === key) acc.push(b);return acc;}, []);}indegree(key) {return [...this.edges.values()].reduce((acc, { a, b }) => {if (b === key) acc++;return acc;}, 0);}outdegree(key) {return [...this.edges.values()].reduce((acc, { a, b }) => {if (a === key) acc++;return acc;}, 0);}}const g = new Graph();g.addNode('a');g.addNode('b');g.addNode('c');g.addNode('d');g.addEdge('a', 'c');g.addEdge('b', 'c');g.addEdge('c', 'b');g.addEdge('d', 'a');g.nodes.map(x => x.value); // ['a', 'b', 'c', 'd'][...g.edges.values()].map(({ a, b }) => `${a} => ${b}`);// ['a => c', 'b => c', 'c => b', 'd => a']g.adjacent('c'); // ['b']g.indegree('c'); // 2g.outdegree('c'); // 1g.hasEdge('d', 'a'); // trueg.hasEdge('a', 'd'); // falseg.removeEdge('c', 'b');[...g.edges.values()].map(({ a, b }) => `${a} => ${b}`);// ['a => c', 'b => c', 'd => a']g.removeNode('c');g.nodes.map(x => x.value); // ['a', 'b', 'd'][...g.edges.values()].map(({ a, b }) => `${a} => ${b}`);// ['d => a']g.setEdgeWeight('d', 'a', 5);g.getEdgeWeight('d', 'a'); // 5
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
function formatDate(date) {return date.toLocaleDateString();}function Comment(props) {return (<div className="Comment"><div className="UserInfo"><imgclassName="Avatar"src={props.author.avatarUrl}alt={props.author.name}/><div className="UserInfo-name">{props.author.name}</div></div><div className="Comment-text">{props.text}</div><div className="Comment-date">{formatDate(props.date)}</div></div>);}const comment = {date: new Date(),text: 'I hope you enjoy learning React!',author: {name: 'Hello Kitty',avatarUrl: 'https://placekitten.com/g/64/64',},};ReactDOM.render(<Commentdate={comment.date}text={comment.text}author={comment.author}/>,document.getElementById('root'));
// There are n rings and each ring is either red, green, or blue. The rings are distributed across ten rods labeled from 0 to 9.// You are given a string rings of length 2n that describes the n rings that are placed onto the rods. Every two characters in rings forms a color-position pair that is used to describe each ring where:// The first character of the ith pair denotes the ith ring's color ('R', 'G', 'B').// The second character of the ith pair denotes the rod that the ith ring is placed on ('0' to '9').// For example, "R3G2B1" describes n == 3 rings: a red ring placed onto the rod labeled 3, a green ring placed onto the rod labeled 2, and a blue ring placed onto the rod labeled 1.// Return the number of rods that have all three colors of rings on them.let rings = "B0B6G0R6R0R6G9";var countPoints = function(rings) {let sum = 0;// Always 10 Rodsfor (let i = 0; i < 10; i++) {if (rings.includes(`B${i}`) && rings.includes(`G${i}`) && rings.includes(`R${i}`)) {sum+=1;}}return sum;};console.log(countPoints(rings));
export const Main = () => {const [title, setTitle] = useState('');return (<ChildComponenttitle={title}onChange={e => setTitle(e.target.value)}/>);};export const ChildComponent = ({ title, onChange }) => {return (<Box component="form" onSubmit={() => {}} noValidate mt={5}><TextFieldfullWidthid="title"label="Title"name="title"autoComplete="title"autoFocuscolor="primary"variant="filled"InputLabelProps={{ shrink: true }}value={title}onChange={onChange}/></Box>);};
const arithmeticProgression = (n, lim) =>Array.from({ length: Math.ceil(lim / n) }, (_, i) => (i + 1) * n );arithmeticProgression(5, 25); // [5, 10, 15, 20, 25]