Apple Hard Interview Questions

In order to track the number of borrowed books, Apple Books needs an effective way to manage the list of borrowed books based on different genres and their borrowing time.
Problem statement: You are given an array of integers books representing the borrowing times in days for different genres of books. Return the number of unique genres that have been borrowed for k or more days.Example 1:
Input: books = [3, 1, 4, 1, 5, 9, 2], k = 3
Output: 4
Explanation: The unique genres with a borrowing time of 3 days or more are 3, 4, 5, and 9.Example 2:
Input: books = [1, 2, 3, 4, 5, 6], k = 5
Output: 2
Explanation: The unique genres with a borrowing time of 5 days or more are 5 and 6.
Constraints:
- 1 <= books.length <= 10^4
- 1 <= books[i] <= 10^5
- 1 <= k <= 10^5

Apple is known for its high-quality media streaming services. The goal of this problem is to create a dynamic viewing experience that adapts to varying bandwidth conditions.
Problem statement: Given an array of integers representing the bandwidth availability over time, find the maximum sum of continuous k bandwidth values that can ensure a smooth streaming experience.Example 1:
Input: bandwidth = [10, 1, 2, 3, 4, 5, 6], k = 3
Output: 15
Explanation: The maximum bandwidth from indices 4 to 6 is 5 + 6 + 4 = 15.Example 2:
Input: bandwidth = [12, 5, 4, 1, 3], k = 2
Output: 17
Explanation: The maximum bandwidth from indices 0 to 1 is 12 + 5 = 17.
Constraints:
- 1 <= bandwidth.length <= 10^4
- 1 <= bandwidth[i] <= 100
- 1 <= k <= bandwidth.length