Function promisification
0 likes • Nov 19, 2022 • 0 views
JavaScript
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const binarySearch = (arr, item) => {let l = 0,r = arr.length - 1;while (l <= r) {const mid = Math.floor((l + r) / 2);const guess = arr[mid];if (guess === item) return mid;if (guess > item) r = mid - 1;else l = mid + 1;}return -1;};binarySearch([1, 2, 3, 4, 5], 1); // 0binarySearch([1, 2, 3, 4, 5], 5); // 4binarySearch([1, 2, 3, 4, 5], 6); // -1
import React, { useState } from 'react' import Welcome from '../components/Welcome' function About() { const [showWelcome, setShowWelcome] = useState(false) return ( <div> {showWelcome ? <Welcome /> : null} </div> <div> {showWelcome && <Welcome /> } </div> ) } export default App
const geometricProgression = (end, start = 1, step = 2) =>Array.from({length: Math.floor(Math.log(end / start) / Math.log(step)) + 1,}).map((_, i) => start * step ** i);geometricProgression(256); // [1, 2, 4, 8, 16, 32, 64, 128, 256]geometricProgression(256, 3); // [3, 6, 12, 24, 48, 96, 192]geometricProgression(256, 1, 4); // [1, 4, 16, 64, 256]
const heapsort = arr => {const a = [...arr];let l = a.length;const heapify = (a, i) => {const left = 2 * i + 1;const right = 2 * i + 2;let max = i;if (left < l && a[left] > a[max]) max = left;if (right < l && a[right] > a[max]) max = right;if (max !== i) {[a[max], a[i]] = [a[i], a[max]];heapify(a, max);}};for (let i = Math.floor(l / 2); i >= 0; i -= 1) heapify(a, i);for (i = a.length - 1; i > 0; i--) {[a[0], a[i]] = [a[i], a[0]];l--;heapify(a, 0);}return a;};heapsort([6, 3, 4, 1]); // [1, 3, 4, 6]
const countSubstrings = (str, searchValue) => {let count = 0,i = 0;while (true) {const r = str.indexOf(searchValue, i);if (r !== -1) [count, i] = [count + 1, r + 1];else return count;}};countSubstrings('tiktok tok tok tik tok tik', 'tik'); // 3countSubstrings('tutut tut tut', 'tut'); // 4
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]