Shortest Subarray to be Removed to Make Array Sorted
<p>Given an integer array <code>arr</code>, remove a subarray (can be empty) from <code>arr</code> such that the remaining elements in <code>arr</code> are <strong>non-decreasing</strong>.</p>

<p>Return <em>the length of the shortest subarray to remove</em>.</p>

<p>A <strong>subarray</strong> is a contiguous subsequence of the array.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> arr = [1,2,3,10,4,2,3,5]
<strong>Output:</strong> 3
<strong>Explanation:</strong> The shortest subarray we can remove is [10,4,2] of length 3. The remaining elements after that will be [1,2,3,3,5] which are sorted.
Another correct solution is to remove the subarray [3,10,4].
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> arr = [5,4,3,2,1]
<strong>Output:</strong> 4
<strong>Explanation:</strong> Since the array is strictly decreasing, we can only keep a single element. Therefore we need to remove a subarray of length 4, either [5,4,3,2] or [4,3,2,1].
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> arr = [1,2,3]
<strong>Output:</strong> 0
<strong>Explanation:</strong> The array is already non-decreasing. We do not need to remove any elements.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= arr.length &lt;= 10<sup>5</sup></code></li>
	<li><code>0 &lt;= arr[i] &lt;= 10<sup>9</sup></code></li>
</ul>
Stack; Array; Two Pointers; Binary Search; Monotonic Stack
class Solution:
    def findLengthOfShortestSubarray(self, arr: List[int]) -> int:
        n = len(arr)
        i, j = 0, n - 1
        while i + 1 < n and arr[i] <= arr[i + 1]:
            i += 1
        while j - 1 >= 0 and arr[j - 1] <= arr[j]:
            j -= 1
        if i >= j:
            return 0
        ans = min(n - i - 1, j)
        for l in range(i + 1):
            r = bisect_left(arr, arr[l], lo=j)
            ans = min(ans, r - l - 1)
        return ans
