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const deepMerge = (a, b, fn) =>[...new Set([...Object.keys(a), ...Object.keys(b)])].reduce((acc, key) => ({ ...acc, [key]: fn(key, a[key], b[key]) }),{});deepMerge({ a: true, b: { c: [1, 2, 3] } },{ a: false, b: { d: [1, 2, 3] } },(key, a, b) => (key === 'a' ? a && b : Object.assign({}, a, b)));// { a: false, b: { c: [ 1, 2, 3 ], d: [ 1, 2, 3 ] } }
class SequentialQueue{ //if you want it to go backwards, too badnext(){return this.i++;}constructor(start = 0){this.i = start;}}const que = new SequentialQueue(0);for(let i = 0; i < 10; i++){console.log(que.next());}
const longestPalindrome = (s) => {if(s.length === 1) return sconst odd = longestOddPalindrome(s)const even = longestEvenPalindrome(s)if(odd.length >= even.length) return oddif(even.length > odd.length) return even};const longestOddPalindrome = (s) => {let longest = 0let longestSubStr = ""for(let i = 1; i < s.length; i++) {let currentLongest = 1let currentLongestSubStr = ""let left = i - 1let right = i + 1while(left >= 0 && right < s.length) {const leftLetter = s[left]const rightLetter = s[right]left--right++if(leftLetter === rightLetter) {currentLongest += 2currentLongestSubStr = s.slice(left+1, right)} else break}if(currentLongest > longest) {if(currentLongestSubStr) longestSubStr = currentLongestSubStrelse longestSubStr = s[i]longest = currentLongest}}return longestSubStr}const longestEvenPalindrome = (s) => {let longest = 0let longestSubStr = ""for(let i = 0; i < s.length - 1; i++) {if(s[i] !== s[i+1]) continue;let currentLongest = 2let currentLongestSubStr = ""let left = i - 1let right = i + 2while(left >= 0 && right < s.length) {const leftLetter = s[left]const rightLetter = s[right]left--right++if(leftLetter === rightLetter) {currentLongest += 2currentLongestSubStr = s.slice(left+1, right)} else break}if(currentLongest > longest) {if(currentLongestSubStr) longestSubStr = currentLongestSubStrelse longestSubStr = s[i] + s[i+1]longest = currentLongest}}return longestSubStr}console.log(longestPalindrome("babad"))
var invertTree = function(root) {const reverseNode = node => {if (node == null) {return null}reverseNode(node.left);reverseNode(node.right);let holdLeft = node.left;node.left = node.right;node.right = holdLeft;return node;}return reverseNode(root);};
function Welcome(props) {return <h1>Hello, {props.name}</h1>;}function App() {return (<div><Welcome name="Sara" /><Welcome name="Cahal" /><Welcome name="Edite" /></div>);}ReactDOM.render(<App />,document.getElementById('root'));
const compactObject = val => {const data = Array.isArray(val) ? val.filter(Boolean) : val;return Object.keys(data).reduce((acc, key) => {const value = data[key];if (Boolean(value))acc[key] = typeof value === 'object' ? compactObject(value) : value;return acc;},Array.isArray(val) ? [] : {});};const obj = {a: null,b: false,c: true,d: 0,e: 1,f: '',g: 'a',h: [null, false, '', true, 1, 'a'],i: { j: 0, k: false, l: 'a' }};compactObject(obj);// { c: true, e: 1, g: 'a', h: [ true, 1, 'a' ], i: { l: 'a' } }