Minimum Number of Removals to Make Mountain 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 `nums`​​​, return _the **minimum** number of elements to remove to make _`nums_​​​_`_ __a **mountain array**._   **Example 1:** **Input:** nums = [1,3,1] **Output:** 0 **Explanation:** The array itself is a mountain array so we do not need to remove any elements. ``` **Example 2:** **Input:** nums = [2,1,1,5,6,2,3,1] **Output:** 3 **Explanation:** One solution is to remove the elements at indices 0, 1, and 5, making the array nums = [1,5,6,3,1]. ```   **Constraints:** - `3 <= nums.length <= 1000` - `1 <= nums[i] <= 109` - It is guaranteed that you can make a mountain array out of `nums`.