/**

* 941. Valid Mountain Array

* https://leetcode.com/problems/valid-mountain-array/

* Difficulty: Easy

*

* Given an array of integers arr, return true if and only if it is a valid mountain array.

*

* Recall that arr is a mountain array if and only if:

* - arr.length >= 3

* - There exists some i with 0 < i < arr.length - 1 such that:

* - arr[0] < arr[1] < ... < arr[i - 1] < arr[i]

* - arr[i] > arr[i + 1] > ... > arr[arr.length - 1]

*/

/**

* @param {number[]} arr

* @return {boolean}

*/

var validMountainArray = function(arr) {

if (arr.length < 3) return false;

const peakIndex = arr.indexOf(Math.max(...arr));

if (peakIndex === 0 || peakIndex === arr.length - 1) return false;

for (let i = 1; i < peakIndex; i++) {

if (arr[i] <= arr[i - 1]) return false;

}

for (let i = peakIndex + 1; i < arr.length; i++) {

if (arr[i] >= arr[i - 1]) return false;

}

return true;

};