JavaScriptTheAlgorithms/Maths/FindMaxRecursion.js at master · run100/JavaScriptTheAlgorithms · GitHub

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/**

* @function findMaxRecursion

* @description This algorithm will find the maximum value of a array of numbers.

* @param {Integer[]} arr Array of numbers

* @param {Integer} left Index of the first element

* @param {Integer} right Index of the last element

* @return {Integer} Maximum value of the array

* @see [Maximum value](https://en.wikipedia.org/wiki/Maximum_value)

* @example findMaxRecursion([1, 2, 4, 5]) = 5

* @example findMaxRecursion([10, 40, 100, 20]) = 100

* @example findMaxRecursion([-1, -2, -4, -5]) = -1

function findMaxRecursion (arr, left, right) {

const len = arr.length

if (len === 0 || !arr) {

return undefined

}

if (left >= len || left < -len || right >= len || right < -len) {

throw new Error('Index out of range')

}

if (left === right) {

return arr[left]

}

// n >> m is equivalent to floor(n / pow(2, m)), floor(n / 2) in this case, which is the mid index

const mid = (left + right) >> 1

const leftMax = findMaxRecursion(arr, left, mid)

const rightMax = findMaxRecursion(arr, mid + 1, right)

// Return the maximum

return Math.max(leftMax, rightMax)

}

export { findMaxRecursion }

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