Is Smallest Subarray to Sort in Every Sliding Window easy or hard?

This problem is typically rated Medium because the brute force idea is simple but the optimal O(n) boundary detection requires recognizing sorted order violations. Understanding prefix maximums, suffix minimums, or monotonic stack patterns is key to solving it efficiently.

Smallest Subarray to Sort in Every Sliding Window Python/Java solution

The solution can be implemented in Python, Java, C++, Go, or TypeScript using the same linear scan idea. Track the running maximum during a forward pass and the running minimum during a backward pass to determine the minimal unsorted region in O(n) time.

How to solve Smallest Subarray to Sort in Every Sliding Window in O(n)?

Scan the array while maintaining the maximum value seen so far. If the current element is smaller than this maximum, it belongs to the unsorted region. Then perform a reverse scan tracking the minimum value from the right; elements larger than this minimum extend the right boundary. These two passes identify the minimal subarray that must be sorted.

What is the best approach for Smallest Subarray to Sort in Every Sliding Window?

The most efficient approach tracks violations of sorted order using a left maximum and right minimum scan. By maintaining the maximum element seen so far from the left and the minimum element from the right, you can detect the smallest boundaries that break sorted order. This method runs in O(n) time with O(n) extra space and avoids repeatedly sorting windows.

Is Smallest Subarray to Sort in Every Sliding Window asked at Google/Amazon/Meta?

Problems involving detecting minimal unsorted subarrays and sliding window analysis appear frequently in interviews at companies like Amazon, Google, and Meta. Variants often test array scanning techniques, monotonic stacks, and boundary detection logic rather than the exact problem statement.

What data structure is used in Smallest Subarray to Sort in Every Sliding Window?

The core solution primarily uses arrays with prefix and suffix tracking. Some variations use a monotonic stack to detect where sorted order breaks. These structures help detect disorder boundaries efficiently without sorting each window.

What is the time complexity of Smallest Subarray to Sort in Every Sliding Window?

The optimal solution runs in O(n) time using two linear passes across the array. One pass tracks the maximum value seen so far from the left, and another tracks the minimum value from the right. Brute force solutions that sort each window typically take O(n * k log k) time.

3555. Smallest Subarray to Sort in Every Sliding Window - Practice Online

You are given an integer array nums and an integer k.

For each contiguous subarray of length k, determine the minimum length of a continuous segment that must be sorted so that the entire window becomes non‑decreasing; if the window is already sorted, its required length is zero.

Return an array of length n − k + 1 where each element corresponds to the answer for its window.

Example 1:

Input: nums = [1,3,2,4,5], k = 3

Output: [2,2,0]

Explanation:

nums[0...2] = [1, 3, 2]. Sort [3, 2] to get [1, 2, 3], the answer is 2.
nums[1...3] = [3, 2, 4]. Sort [3, 2] to get [2, 3, 4], the answer is 2.
nums[2...4] = [2, 4, 5] is already sorted, so the answer is 0.

Example 2:

Input: nums = [5,4,3,2,1], k = 4

Output: [4,4]

Explanation:

nums[0...3] = [5, 4, 3, 2]. The whole subarray must be sorted, so the answer is 4.
nums[1...4] = [4, 3, 2, 1]. The whole subarray must be sorted, so the answer is 4.

Constraints:

1 <= nums.length <= 1000
1 <= k <= nums.length
1 <= nums[i] <= 10⁶