Clone an array
0 likes • Nov 19, 2022 • 0 views
JavaScript
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const head = arr => (arr && arr.length ? arr[0] : undefined);head([1, 2, 3]); // 1head([]); // undefinedhead(null); // undefinedhead(undefined); // undefined
class TreeNode {constructor(data, depth) {this.data = data;this.children = [];this.depth = depth;}}function buildNaryTree(hosts) {const nodeMap = {};// Step 1: Create a map of nodes using fqdn as the keyhosts.forEach((host) => {nodeMap[host.fqdn] = new TreeNode(host, 0); // Initialize depth to 0});// Step 2: Iterate through the array and add each node to its parent's list of childrenhosts.forEach((host) => {if (host.displayParent) {if (nodeMap[host.displayParent]) {const parent = nodeMap[host.displayParent];const node = nodeMap[host.fqdn];node.depth = parent.depth + 1; // Update the depthparent.children.push(node);} else {console.error(`Parent with fqdn ${host.displayParent} not found for ${host.fqdn}`);}}});// Find the root nodes (nodes with no parent)const rootNodes = hosts.filter((host) => !host.displayParent).map((host) => nodeMap[host.fqdn]);return rootNodes;}function treeToObjects(node) {const result = [];function inOrder(node) {if (!node) {return;}// Visit the current node and add it to the resultresult.push(node.data);// Visit children nodes firstnode.children.forEach((child) => {inOrder(child);});}inOrder(node);return result;}// Usage exampleconst hosts = [{fqdn: 'fqdn_1',display_name: 'Host 1',},{fqdn: 'fqdn_2',display_name: 'Host 2',displayParent: 'fqdn_1',},{fqdn: 'fqdn_3',display_name: 'Host 3'},{fqdn: 'fqdn_4',display_name: 'Host 4',displayParent: 'fqdn_3',},{fqdn: 'fqdn_5',display_name: 'Host 5',displayParent: 'fqdn_1',},];const tree = buildNaryTree(hosts);// Function to convert the tree to an array of objectsfunction convertTreeToArray(nodes) {const result = [];nodes.forEach((node) => {result.push(...treeToObjects(node));});return result;}// Convert the tree back to an array of objectsconst arrayFromTree = convertTreeToArray(tree);console.log(arrayFromTree);
// promisify(f, true) to get array of resultsfunction promisify(f, manyArgs = false) {return function (...args) {return new Promise((resolve, reject) => {function callback(err, ...results) { // our custom callback for fif (err) {reject(err);} else {// resolve with all callback results if manyArgs is specifiedresolve(manyArgs ? results : results[0]);}}args.push(callback);f.call(this, ...args);});};}// usage:f = promisify(f, true);f(...).then(arrayOfResults => ..., err => ...);
const bucketSort = (arr, size = 5) => {const min = Math.min(...arr);const max = Math.max(...arr);const buckets = Array.from({ length: Math.floor((max - min) / size) + 1 },() => []);arr.forEach(val => {buckets[Math.floor((val - min) / size)].push(val);});return buckets.reduce((acc, b) => [...acc, ...b.sort((a, b) => a - b)], []);};bucketSort([6, 3, 4, 1]); // [1, 3, 4, 6]
const gcd = (...arr) => {const _gcd = (x, y) => (!y ? x : gcd(y, x % y));return [...arr].reduce((a, b) => _gcd(a, b));};gcd(8, 36); // 4gcd(...[12, 8, 32]); // 4
const primes = num => {let arr = Array.from({ length: num - 1 }).map((x, i) => i + 2),sqroot = Math.floor(Math.sqrt(num)),numsTillSqroot = Array.from({ length: sqroot - 1 }).map((x, i) => i + 2);numsTillSqroot.forEach(x => (arr = arr.filter(y => y % x !== 0 || y === x)));return arr;};primes(10); // [2, 3, 5, 7]