Meta Mobile Engineer Interview Questions

In Instagram, users post Stories that need to be efficiently retrieved based on user interactions and visibility. You are tasked with implementing a function that simulates an in-order traversal of a binary tree representing user stories.
Problem Statement: Given a binary tree where each node contains a user's story with a title represented as a string, return an array of titles in in-order traversal. Each story node has left and right pointers corresponding to older and newer stories.
Example 1:
Input: root = ["Story1", "Story2", "Story3"]
Output: ["Story2", "Story1", "Story3"]
Explanation: The in-order traversal gives the order of stories read by a user.
Example 2:
Input: root = ["StoryA", "StoryB", "StoryC"]
Output: ["StoryB", "StoryA", "StoryC"]
Constraints:
- 1 <= number of stories <= 1000
- Each story title is at most 100 characters.

Meta’s platforms, like Instagram, need to efficiently manage memory for smooth scrolling through large feeds. In this task, you will implement a sliding window technique to maintain a dynamic range of elements displayed in the feed.
Problem Statement: Given an array of integers likes representing the number of likes each post received in the feed, find the maximum number of likes within any contiguous subarray of size k. Return the result as an integer.
Example 1:
Input: likes = [5, 1, 3, 7, 3, 2, 8], k = 3
Output: 18
Explanation: The maximum sum of likes in any sliding window of size 3 is from the subarray [7, 3, 8].
Example 2:
Input: likes = [2, 4, 1, 8, 3, 6], k = 2
Output: 12
Explanation: The maximum sum of likes in any sliding window of size 2 is from the subarray [8, 4].
Constraints:
- 1 <= likes.length <= 10^5
- 0 <= likes[i] <= 10^4
- 1 <= k <= likes.length