Find the Power of K-Size Subarrays I

Problem Description

You are given an array of integers nums of length n and a positive integer k. The power of an array is defined as:

• Its maximum element if all of its elements are consecutive and sorted in ascending order.
• -1 otherwise.

You need to find the power of all subarrays of nums of size k. Return an integer array results of size n - k + 1, where results[i] is the power of nums[i..(i + k - 1)].

Key Insights

• A subarray is considered powerful if its elements are consecutive integers in ascending order.
• To check if a subarray is valid, we can sort the subarray and check the difference between the maximum and minimum elements.
• We can utilize a sliding window technique to efficiently assess each subarray of size k.

Space and Time Complexity

Time Complexity: O(n * k log k) in the worst case due to sorting each subarray. Space Complexity: O(k) for storing the current subarray.

Solution

To solve the problem, we will use a sliding window approach to generate each subarray of size k. For each subarray:

1. Sort the subarray and check if the maximum minus the minimum equals k - 1 (which ensures the elements are consecutive).
2. If true, return the maximum element; otherwise, return -1.

This approach ensures we efficiently check each subarray's properties while maintaining the required conditions.

Code Solutions