Meta E4 Product Screen + Onsite

This question likely involved concepts related to internationalization (i18n), potentially covering system design aspects, API considerations, or implementation details for supporting multiple languages and regions within a software product. Given it was a product screen, it might have involved discussions around product implications or technical solutions for i18n.

Given the root node of a binary search tree and two integers low and high, return the sum of all nodes' values that are in the inclusive range [low, high].

Given two strings s and t of lengths m and n respectively, return the minimum window substring of s such that every character in t (including duplicates) is included in the window. If there is no such substring, return the empty string "".

Given the root of a binary tree, return the length of the diameter of the tree. The diameter of a binary tree is the length of the longest path between any two nodes in a tree. This path may or may not pass through the root.

You are given the root of a binary tree where each node has a value 0 to 9. Each root-to-leaf path represents a number. For example, if the path is 1->2->3, the number is 123. Return the total sum of all root-to-leaf numbers.

Implement a function to calculate the dot product of two arrays or vectors. The 'array method' specification suggests a direct implementation rather than focusing on sparse matrix optimizations, though that could have been an extension.

Design a system for booking tickets, with a primary focus on defining the API endpoints and the database schema. This typically involves considerations for user management, event/ticket management, the booking process, payment integration, and handling concurrency.