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Commit 820f8e9

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jhonDoe15raklaptudirm
andauthored
merge: Create firstRelativeMaxPointInArray.js (#772)
* Create first_relative_max_point_in_array.js go over randomly generated array and print first spike or maximum point index in it runs in O(log(n)) * rename file to match requested casing * add comments I prefer SOLID standards so that's why didn't add them at first but due to the repository requirements was needed to be added * remove template unrelated comments * Update equals check to match JavaScript standards * create file skafolding and adjust filename to reflect main function * using newer node version * add tests * add last line as empty line * style changes * move algorithm tests to test folder * revert to old package lock file * chore: add ending line feed Co-authored-by: Rak Laptudirm <raklaptudirm@gmail.com>
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/**
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* [LocalMaxima](https://www.geeksforgeeks.org/find-indices-of-all-local-maxima-and-local-minima-in-an-array/) is an algorithm to find relative bigger numbers compared to their neighbors
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*
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* Notes:
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* - works by using divide and conquer
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* - the function gets the array A with n Real numbersand returns the local max point index (if more than one exists return the first one)
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*
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* @complexity: O(log(n)) (on average )
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* @complexity: O(log(n)) (worst case)
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* @flow
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*/
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const findMaxPointIndex = (array, rangeStartIndex, rangeEndIndex, originalLength) => {
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// find index range middle point
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const middleIndex = rangeStartIndex + parseInt((rangeEndIndex - rangeStartIndex) / 2)
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// handle array bounds
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if ((middleIndex === 0 || array[middleIndex - 1] <= array[middleIndex]) &&
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(middleIndex === originalLength - 1 || array[middleIndex + 1] <= array[middleIndex])) {
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return middleIndex
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} else if (middleIndex > 0 && array[middleIndex - 1] > array[middleIndex]) {
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return findMaxPointIndex(array, rangeStartIndex, (middleIndex - 1), originalLength)
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} else {
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// regular local max
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return findMaxPointIndex(array, (middleIndex + 1), rangeEndIndex, originalLength)
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}
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}
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const LocalMaximomPoint = (A) => findMaxPointIndex(A, 0, A.length - 1, A.length)
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export { LocalMaximomPoint }
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import { LocalMaximomPoint } from '../LocalMaximomPoint'
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describe('LocalMaximomPoint tests', () => {
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it('test boundry maximom points - last element', () => {
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const Array = [1, 2, 3, 4, 5, 6, 12]
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expect(LocalMaximomPoint(Array)).toEqual(6)
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})
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it('test boundry maximom points - first element', () => {
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const Array2 = [13, 6, 5, 4, 3, 2, 1]
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expect(LocalMaximomPoint(Array2)).toEqual(0)
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})
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it('test boundry maximom points - should find first maximom point from the top', () => {
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// Test a mix of number types (i.e., positive/negative, numbers with decimals, fractions)
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const Array = [13, 2, 3, 4, 5, 6, 12]
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expect(LocalMaximomPoint(Array)).toEqual(6)
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})
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it('test inner points - second element', () => {
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const Array2 = [13, 16, 5, 4, 3, 2, 1]
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expect(LocalMaximomPoint(Array2)).toEqual(1)
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})
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it('test inner points - element some where in the middle', () => {
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const Array2 = [13, 16, 5, 41, 3, 2, 1]
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expect(LocalMaximomPoint(Array2)).toEqual(3)
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})
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})

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