Create findRelativeMaximumPointCount.js #771

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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
	*
	* Notes:
	* - like the other similar local maxima search function find relative maxima points in array but doesnt stop at one but returns total point count
	* - runs on array A of size n and returns the local maxima count using divide and conquer methodology
	*
	* @complexity: O(n) (on average )
	* @complexity: O(n) (worst case)
	* @flow
	*/

	// check if returned index is a local maxima
	const IsMaximumPoint = (array, index) => {
	// handle array bounds
	// array start
	if (index === 0) {
	return array[index] > array[index + 1]
	// array end
	} else if (index === array.length - 1) {
	return array[index] > array[index - 1]
	// handle index inside array bounds
	} else {
	return array[index] > array[index + 1] && array[index] > array[index - 1]
	}
	}

	const CountLocalMaximumPoints = (array, startIndex, endIndex) => {
	// stop check in divide and conquer recursion
	if (startIndex === endIndex) {
	return IsMaximumPoint(array, startIndex) ? 1 : 0
	}

	// handle the two halves
	const middleIndex = parseInt((startIndex + endIndex) / 2)
	return CountLocalMaximumPoints(array, startIndex, middleIndex) +
	CountLocalMaximumPoints(array, middleIndex + 1, endIndex)
	}

	const NumberOfLocalMaximumPoints = (A) => CountLocalMaximumPoints(A, 0, A.length - 1)

	export { NumberOfLocalMaximumPoints }

43 changes: 43 additions & 0 deletions Data-Structures/Array/test/NumberOfLocalMaximumPoints.test.js

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	import { NumberOfLocalMaximumPoints } from '../NumberOfLocalMaximumPoints'

	describe('LocalMaximomPoint tests', () => {
	it('test boundry maximom points - last element', () => {
	const Array = [1, 2, 3, 4, 5, 6, 12]
	expect(NumberOfLocalMaximumPoints(Array)).toEqual(1)
	})

	it('test boundry maximom points - first element', () => {
	const Array = [13, 6, 5, 4, 3, 2, 1]
	expect(NumberOfLocalMaximumPoints(Array)).toEqual(1)
	})

	it('test boundry maximom points - both boundries have maximum points', () => {
	// Test a mix of number types (i.e., positive/negative, numbers with decimals, fractions)
	const Array = [13, 2, 3, 4, 5, 6, 12]
	expect(NumberOfLocalMaximumPoints(Array)).toEqual(2)
	})

	it('multiple maximom points in the middle', () => {
	// Test a mix of number types (i.e., positive/negative, numbers with decimals, fractions)
	const Array = [1, 3, 2, 5, 6, 9, 2, 7, 12, 1, 0]
	expect(NumberOfLocalMaximumPoints(Array)).toEqual(3)
	})

	it('multiple maximom points in the middle with one at end', () => {
	// Test a mix of number types (i.e., positive/negative, numbers with decimals, fractions)
	const Array = [1, 3, 2, 5, 6, 9, 2, 7, 12, 1, 10]
	expect(NumberOfLocalMaximumPoints(Array)).toEqual(4)
	})

	it('multiple maximom points in the middle with one at start', () => {
	// Test a mix of number types (i.e., positive/negative, numbers with decimals, fractions)
	const Array = [10, 3, 2, 5, 6, 9, 2, 7, 12, 1, 0]
	expect(NumberOfLocalMaximumPoints(Array)).toEqual(3)
	})

	it('multiple maximom points in the middle with two more at both ends', () => {
	// Test a mix of number types (i.e., positive/negative, numbers with decimals, fractions)
	const Array = [10, 3, 11, 5, 6, 9, 2, 7, 12, 1, 10]
	expect(NumberOfLocalMaximumPoints(Array)).toEqual(5)
	})
	})

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