Shortest Subarray to be Removed to Make Array Sorted — LeetCode 1574 Python Solution

The problem

Given an integer array arr, remove a subarray (can be empty) from arr such that the remaining elements in arr are non-decreasing. Return the length of the shortest subarray to remove.

Example

Input

arr = [1,2,3,10,4,2,3,5]

Output

3

Explanation

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.

Python solution

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

Complexity

Pattern: Stack

When the most recent unresolved thing is the one that matters, use a stack. LeetCode 1574. Shortest Subarray to be Removed to Make Array Sorted is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Stack.

The stack guide has the Python template for the pattern and the 194 LeetCode problems that use it.

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