845. Longest Mountain in Array

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 subar