Roblox Interview Questions

1. Background: In Roblox, user engagement is a key factor in maintaining a vibrant gaming platform. Developers need to identify the best games to recommend to users based on their preferences and previous activities.
2. Problem statement: You are given a sorted list of game ratings and a specific rating target. Implement a function to find the index of the lowest rating that is greater than or equal to target. If no such rating exists, return -1.
3. Function/class signature:
- def find_best_game_index(ratings: List[int], target: int) -> int:
4. Example 1:
- Input: ratings = [1, 3, 5, 7, 9], target = 6
- Output: 3
- Explanation: The first rating greater than or equal to 6 is 7, which is at index 3.
5. Example 2:
- Input: ratings = [1, 3, 5, 7, 9], target = 10
- Output: -1
- Explanation: There are no ratings greater than or equal to 10.
6. Constraints:
- 0 <= len(ratings) <= 10^4
- -10^4 <= ratings[i] <= 10^4
- The array ratings will be sorted in ascending order.

Background: Revenue generation is crucial for Roblox as a platform for developers and creators to monetize their games. Understanding how to optimize revenue from in-game purchases can significantly impact overall earnings.
Problem statement: Given an array of integers representing the revenue from in-game items, you need to determine the maximum revenue that can be generated without selling two consecutive items. This simulates the constraint of not being able to sell items that share the same game session.
Function/class signature:

• def maximize_revenue(revenue: List[int]) -> int:

Example 1:

• Input: [3, 2, 5, 10, 7]


• Output: 15


• Explanation: Sell items with revenue 3, 10, and 2 (total revenue: 15).

Example 2:

• Input: [1, 2, 3, 1]


• Output: 4


• Explanation: Sell items with revenue 1, 3 (total revenue: 4).

Constraints:

• 1 <= len(revenue) <= 1000


• 0 <= revenue[i] <= 1000


• The array will not be empty.

Background: In Roblox, games often have complex scenes represented as trees where each node might represent an object, character, or relationship. Traversing these trees effectively is essential for gameplay mechanics, like determining all possible outcomes based on players' actions.
Problem statement: Given a binary tree, implement a function that returns all root-to-leaf paths. Each path should be represented as a list of node values. A leaf is defined as a node with no children.
Function/class signature:

• def binary_tree_paths(root: Optional[TreeNode]) -> List[str]:

Example 1:

• Input: root = [1,2,3,null,5]


• Output: ['1->2->5', '1->3']


• Explanation: The paths from root 1 to leaves 5 and 3 are valid.

Example 2:

• Input: root = [1]


• Output: ['1']


• Explanation: The only path is the root itself.

Constraints:

• The number of nodes in the tree is in the range [1, 100].


• Node values are in the range of [-1000, 1000].

Background: In the gaming environment of Roblox, players often create diverse gameplay experiences, and tracking player activity efficiently is crucial. Understanding the patterns of active gameplay can help optimize game performance and enhance user engagement.
Problem statement: Given a string s representing a sequence of characters in Roblox, full of various gameplay actions, find the length of the longest substring without repeating characters. This substring represents a period of unique gameplay actions without repetition.
Function/class signature:

• def length_of_longest_substring(s: str) -> int:

Example 1:
Input: "abcabcbb"
Output: 3
Explanation: The longest substring without repeating characters is "abc", with length 3.Example 2:
Input: "bbbbb"
Output: 1
Explanation: The longest substring without repeating characters is "b", with length 1.Constraints:

• 0 <= len(s) <= 50,000


• s consists of English letters, digits, symbols, and spaces.

1. Background: Roblox manages many tasks and events across different games, each with its own priority. Efficiently scheduling these tasks ensures that high-priority tasks are processed first, improving overall game performance and user experience.
2. Problem statement: You are tasked with optimizing the scheduling of tasks in Roblox based on their priority. Each task has a startTime, endTime, and a priority level. Your goal is to maximize the number of high-priority tasks that can be scheduled without overlapping. Overlapping occurs when one task's startTime is less than another's endTime.
3. Function/class signature:
- def schedule_tasks(tasks: List[Tuple[int, int, int]]) -> List[Tuple[int, int, int]]:
4. Example 1:
- Input: [(1, 3, 1), (2, 5, 2), (4, 6, 1), (6, 8, 2)]
- Output: [(1, 3, 1), (4, 6, 1)]
- Explanation: Tasks (1, 3, 1) and (4, 6, 1) are scheduled without overlaps, maximizing high-priority task execution.
5. Example 2:
- Input: [(1, 4, 3), (3, 5, 2), (5, 7, 2), (8, 10, 3)]
- Output: [(1, 4, 3), (5, 7, 2), (8, 10, 3)]
- Explanation: First, the highest priority task (1, 4, 3) is selected, then (5, 7, 2), followed by (8, 10, 3) without overlap.
6. Constraints:
- Each start and end time is a positive integer.
- Tasks will have a priority between 1 and 5 (inclusive).
- The number of tasks will be at most 1000.