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new StringBuilder(hi).reverse().toString()
const luhnCheck = num => {let arr = (num + '').split('').reverse().map(x => parseInt(x));let lastDigit = arr.splice(0, 1)[0];let sum = arr.reduce((acc, val, i) => (i % 2 !== 0 ? acc + val : acc + ((val *= 2) > 9 ? val - 9 : val)),0);sum += lastDigit;return sum % 10 === 0;};luhnCheck('4485275742308327'); // trueluhnCheck(6011329933655299); // trueluhnCheck(123456789); // false
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
arr = [] // empty arrayconst isEmpty = arr => !Array.isArray(arr) || arr.length === 0;// ExamplesisEmpty([]); // trueisEmpty([1, 2, 3]); // false
/*** @param {number[]} nums* @return {number[]}*/var productExceptSelf = function(nums) {var output = [];var leftMult = 1;var rightMult = 1;for (var i=nums.length - 1; i >= 0; i--) {output[i] = rightMult;rightMult *= nums[i];console.log({output: JSON.stringify(output), i})}for (var j=0; j < nums.length; j++) {output[j] *= leftMult;leftMult *= nums[j];console.log({output: JSON.stringify(output), j})}return output;};console.log(productExceptSelf([1, 2, 3, 4]))
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]