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Commit 9ad93c7

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jhonDoe15raklaptudirm
andauthored
merge: Create findRelativeMaximumPointCount.js (#771)
* Create find_relative_maximum_point_count.js print number of relative maximum points in array runs in O(n) * rename file to match requested casing * add inline comments and greater documentation * fix wrong reference to algorithm explanation * remove live code and fix function misnaming * add multiple cases tests * add last line as empty line * git pull * style changes * move tests to test folder * chore: fix spelling * fix package-lock * revert to old lock file * chore: add line feed Co-authored-by: Rak Laptudirm <raklaptudirm@gmail.com>
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/**
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* [NumberOfLocalMaximumPoints](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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* - like the other similar local maxima search function find relative maxima points in array but doesnt stop at one but returns total point count
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* - runs on array A of size n and returns the local maxima count using divide and conquer methodology
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*
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* @complexity: O(n) (on average )
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* @complexity: O(n) (worst case)
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* @flow
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*/
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// check if returned index is a local maxima
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const IsMaximumPoint = (array, index) => {
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// handle array bounds
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// array start
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if (index === 0) {
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return array[index] > array[index + 1]
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// array end
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} else if (index === array.length - 1) {
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return array[index] > array[index - 1]
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// handle index inside array bounds
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} else {
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return array[index] > array[index + 1] && array[index] > array[index - 1]
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}
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}
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const CountLocalMaximumPoints = (array, startIndex, endIndex) => {
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// stop check in divide and conquer recursion
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if (startIndex === endIndex) {
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return IsMaximumPoint(array, startIndex) ? 1 : 0
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}
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// handle the two halves
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const middleIndex = parseInt((startIndex + endIndex) / 2)
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return CountLocalMaximumPoints(array, startIndex, middleIndex) +
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CountLocalMaximumPoints(array, middleIndex + 1, endIndex)
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}
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const NumberOfLocalMaximumPoints = (A) => CountLocalMaximumPoints(A, 0, A.length - 1)
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export { NumberOfLocalMaximumPoints }
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import { NumberOfLocalMaximumPoints } from '../NumberOfLocalMaximumPoints'
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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(NumberOfLocalMaximumPoints(Array)).toEqual(1)
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})
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it('test boundry maximom points - first element', () => {
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const Array = [13, 6, 5, 4, 3, 2, 1]
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expect(NumberOfLocalMaximumPoints(Array)).toEqual(1)
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})
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it('test boundry maximom points - both boundries have maximum points', () => {
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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(NumberOfLocalMaximumPoints(Array)).toEqual(2)
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})
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it('multiple maximom points in the middle', () => {
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// Test a mix of number types (i.e., positive/negative, numbers with decimals, fractions)
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const Array = [1, 3, 2, 5, 6, 9, 2, 7, 12, 1, 0]
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expect(NumberOfLocalMaximumPoints(Array)).toEqual(3)
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})
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it('multiple maximom points in the middle with one at end', () => {
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// Test a mix of number types (i.e., positive/negative, numbers with decimals, fractions)
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const Array = [1, 3, 2, 5, 6, 9, 2, 7, 12, 1, 10]
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expect(NumberOfLocalMaximumPoints(Array)).toEqual(4)
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})
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it('multiple maximom points in the middle with one at start', () => {
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// Test a mix of number types (i.e., positive/negative, numbers with decimals, fractions)
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const Array = [10, 3, 2, 5, 6, 9, 2, 7, 12, 1, 0]
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expect(NumberOfLocalMaximumPoints(Array)).toEqual(3)
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})
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it('multiple maximom points in the middle with two more at both ends', () => {
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// Test a mix of number types (i.e., positive/negative, numbers with decimals, fractions)
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const Array = [10, 3, 11, 5, 6, 9, 2, 7, 12, 1, 10]
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expect(NumberOfLocalMaximumPoints(Array)).toEqual(5)
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})
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})

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