Express Login Endpoint
0 likes • Mar 11, 2021
JavaScript
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const linearSearch = (arr, item) => {for (const i in arr) {if (arr[i] === item) return +i;}return -1;};linearSearch([2, 9, 9], 9); // 1linearSearch([2, 9, 9], 7); // -1
const getSubsets = arr => arr.reduce((prev, curr) => prev.concat(prev.map(k => k.concat(curr))), [[]]);// ExamplesgetSubsets([1, 2]); // [[], [1], [2], [1, 2]]getSubsets([1, 2, 3]); // [[], [1], [2], [1, 2], [3], [1, 3], [2, 3], [1, 2, 3]]
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]
const getURLParameters = url =>(url.match(/([^?=&]+)(=([^&]*))/g) || []).reduce((a, v) => ((a[v.slice(0, v.indexOf('='))] = v.slice(v.indexOf('=') + 1)), a),{});
const kMeans = (data, k = 1) => {const centroids = data.slice(0, k);const distances = Array.from({ length: data.length }, () =>Array.from({ length: k }, () => 0));const classes = Array.from({ length: data.length }, () => -1);let itr = true;while (itr) {itr = false;for (let d in data) {for (let c = 0; c < k; c++) {distances[d][c] = Math.hypot(...Object.keys(data[0]).map(key => data[d][key] - centroids[c][key]));}const m = distances[d].indexOf(Math.min(...distances[d]));if (classes[d] !== m) itr = true;classes[d] = m;}for (let c = 0; c < k; c++) {centroids[c] = Array.from({ length: data[0].length }, () => 0);const size = data.reduce((acc, _, d) => {if (classes[d] === c) {acc++;for (let i in data[0]) centroids[c][i] += data[d][i];}return acc;}, 0);for (let i in data[0]) {centroids[c][i] = parseFloat(Number(centroids[c][i] / size).toFixed(2));}}}return classes;};kMeans([[0, 0], [0, 1], [1, 3], [2, 0]], 2); // [0, 1, 1, 0]
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]