Given an integer array arr, return the length of the longest contiguous subarray that forms a mountain.

A subarray arr[l..r] is a mountain if all of the following are true:
A mountain has length at least $3$.
There exists an index p with l < p < r such that arr[l] < arr[l+1] < ... < arr[p] and arr[p] > arr[p+1] > ... > arr[r].
In other words, the values strictly increase up to a single peak, then strictly decrease after the peak.

If no mountain exists in arr, return $0$.

Note: Consider whether you can solve this in a single pass using $O(1)$ extra space.

Constraints:

• $1 \leq$ arr.length $\leq 10^4$

• $0 \leq$ arr[i] $\leq 10^4$

Now, let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:

We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

Implement your solution in the following coding playground.