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const nums = [1, 2, 3];const strs = Array.from('est');nums.push(6);nums.push(4, 9);strs.unshift('t');nums.length; // 6nums[nums.length - 1]; // 9strs[0]; // 't'strs[2]; // 's'nums.slice(1, 3); // [2, 3]nums.map(n => n * 2); // [2, 4, 6, 12, 8, 18]nums.filter(n => n % 2 === 0); // [2, 6, 4]nums.reduce((a, n) => a + n, 0); // 25strs.reverse(); // ['t', 's', 'e', 't']strs.join(''); // 'test'const nums = new Set([1, 2, 3]);nums.add(4);nums.add(1);nums.add(5);nums.add(4);nums.size; // 5nums.has(4); // truenums.delete(4);nums.has(4); // false[...nums]; // [1, 2, 3, 5]nums.clear();nums.size; // 0const items = new Map([[1, { name: 'John' }],[2, { name: 'Mary' }]]);items.set(4, { name: 'Alan' });items.set(2, { name: 'Jeff' });items.size; // 3items.has(4); // trueitems.get(2); // { name: 'Jeff' }items.delete(2);items.size; // 2[...items.keys()]; // [1, 4][...items.values()]; // [{ name: 'John' }, { name: 'Alan' }]items.clear();items.size; // 0
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 permutations = arr => {if (arr.length <= 2) return arr.length === 2 ? [arr, [arr[1], arr[0]]] : arr;return arr.reduce((acc, item, i) =>acc.concat(permutations([...arr.slice(0, i), ...arr.slice(i + 1)]).map(val => [item,...val,])),[]);};permutations([1, 33, 5]);// [ [1, 33, 5], [1, 5, 33], [33, 1, 5], [33, 5, 1], [5, 1, 33], [5, 33, 1] ]
const euclideanDistance = (a, b) =>Math.hypot(...Object.keys(a).map(k => b[k] - a[k]));euclideanDistance([1, 1], [2, 3]); // ~2.2361euclideanDistance([1, 1, 1], [2, 3, 2]); // ~2.4495
function printHeap(heap, index, level) {if (index >= heap.length) {return;}console.log(" ".repeat(level) + heap[index]);printHeap(heap, 2 * index + 1, level + 1);printHeap(heap, 2 * index + 2, level + 1);}//You can call this function by passing in the heap array and the index of the root node, which is typically 0, and level = 0.let heap = [3, 8, 7, 15, 17, 30, 35, 2, 4, 5, 9];printHeap(heap,0,0)
const quickSort = arr => {const a = [...arr];if (a.length < 2) return a;const pivotIndex = Math.floor(arr.length / 2);const pivot = a[pivotIndex];const [lo, hi] = a.reduce((acc, val, i) => {if (val < pivot || (val === pivot && i != pivotIndex)) {acc[0].push(val);} else if (val > pivot) {acc[1].push(val);}return acc;},[[], []]);return [...quickSort(lo), pivot, ...quickSort(hi)];};console.log(quickSort([1, 6, 1, 5, 3, 2, 1, 4])) // [1, 1, 1, 2, 3, 4, 5, 6]