public class Solution
extends Object
845 - Longest Mountain in Array\.
Medium
You may recall that an array `arr` is a **mountain array** if and only if:
* `arr.length >= 3`
* There exists some index `i` ( **0-indexed** ) 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]`
Given an integer array `arr`, return _the length of the longest subarray, which is a mountain_. Return `0` if there is no mountain subarray.
**Example 1:**
**Input:** arr = [2,1,4,7,3,2,5]
**Output:** 5
**Explanation:** The largest mountain is [1,4,7,3,2] which has length 5.
**Example 2:**
**Input:** arr = [2,2,2]
**Output:** 0
**Explanation:** There is no mountain.
**Constraints:**
* 1 <= arr.length <= 104
* 0 <= arr[i] <= 104
**Follow up:**
* Can you solve it using only one pass?
* Can you solve it in `O(1)` space?