Meta VO Interview Questions: Subarray Sum Equals K, Tree Visit Time, and Longest Vacation with PTO

Given an array of integers nums and an integer k, return the total number of subarrays whose sum equals k.

A subarray is a contiguous non-empty sequence of elements within an array.

Example 1:

Input: nums = [1,1,1], k = 2
Output: 2

Example 2:

Input: nums = [1,2,3], k = 3
Output: 2

Given a tree, how long will it take to visit all X nodes optimally?

Traversing one edge takes 1 unit of time. You must return back to the root (Start).

In the tree above, the answer is 6.

Given a calendar year represented as a char array that contains either H or W, where:

• H = Holiday
• W = Workday

Given a number of Personal Time-Off days (PTO), maximize the length of the longest vacation you can take.

Example:

[W, H, H, W, W, H, W], PTO = 2
Your maximum vacation is 5 days.

These Meta VO questions combine three common patterns: prefix sum with a hash map for counting subarrays whose sum equals k, tree traversal cost modeling for visiting all target nodes and returning to the root, and a sliding window / two-pointer approach for maximizing the longest vacation by using PTO days to cover workdays. The key is to translate each story into a standard interview pattern and then optimize for linear-time scanning whenever possible.