public class Solution
extends Object
941 - Valid Mountain Array\.
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]`
**Example 1:**
**Input:** arr = [2,1]
**Output:** false
**Example 2:**
**Input:** arr = [3,5,5]
**Output:** false
**Example 3:**
**Input:** arr = [0,3,2,1]
**Output:** true
**Constraints:**
* 1 <= arr.length <= 104
* 0 <= arr[i] <= 104