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>
This commit is contained in:
jhonDoe15
2021-10-28 09:45:01 +03:00
committed by GitHub
parent 00900f1446
commit 9ad93c7b28
2 changed files with 85 additions and 0 deletions

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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 }