Roblox Coding Interview Questions
26 Roblox coding interview problems with full optimal solutions — 16 easy, 8 medium, 2 hard. Every problem ships with multiple approaches (brute-force first, then the optimal), complexity tables for each, company-specific tips on what an Roblox interviewer values, and a FAQ section.
Showing 26 problems of 26
- #15mediumfoundational
15. Number of Islands
Count connected land regions in a binary grid — Roblox uses this pattern to identify distinct terrain chunks when generating and streaming open-world maps to millions of concurrent players.
- #16easyfoundational
16. Flood Fill
Recolor a connected region starting from a source pixel — the same flood-fill primitive Roblox Studio uses to paint terrain biomes and propagate block-color changes across adjacent voxels.
- #17easyfoundational
17. Climbing Stairs
Count distinct ways to reach the top taking 1 or 2 steps at a time — Roblox references this DP warmup when discussing how the engine enumerates valid move combinations for character pathfinding constraints.
- #18mediumfoundational
18. Course Schedule
Detect cycles in a directed prerequisite graph to determine if all courses can be finished — Roblox applies the same topological-sort logic to resolve asset-loading dependency chains in its streaming engine.
- #19mediumfoundational
19. Word Search
Find whether a word exists in a 2D character grid following adjacent cells — Roblox uses the same constrained-path DFS to validate item-placement patterns and check chat-filter word formations across tiled regions.
- #20mediumfoundational
20. LRU Cache
Design a fixed-capacity cache that evicts the least recently used item — the exact structure Roblox's asset server uses to keep hot game assets in memory while dropping stale ones as thousands of players load different virtual worlds.
- #21mediumfoundational
21. Top K Frequent Elements
Return the k most frequent values from an array — Roblox uses this pattern to surface trending game items, rank popular avatar accessories, and identify the most-crashed experiences from telemetry event streams.
- #22mediumfoundational
22. Implement Trie (Prefix Tree)
Build a prefix tree supporting insert, search, and startsWith — Roblox applies tries for autocomplete in the asset catalog, fast chat-filter prefix matching, and resolving shortened asset-name queries across millions of game items.
- #23hardfoundational
23. Word Ladder
Find the shortest transformation sequence between two words, changing one letter at a time — Roblox draws on this BFS-on-implicit-graph pattern when computing minimum edit-distance hops in their natural-language chat moderation and avatar-name suggestion systems.
- #24hardfoundational
24. Alien Dictionary
Derive character ordering rules from a sorted alien-language word list using topological sort — Roblox applies the same dependency-extraction technique to infer asset-load ordering from observed streaming sequences across game worlds.
- #25mediumfoundational
25. Meeting Rooms II
Find the minimum number of rooms needed to hold all meetings without overlap — Roblox applies the same interval-scheduling logic to allocate game servers and physics simulation slots across concurrent player sessions.
- #26mediumfoundational
26. Game of Life
Simulate one generation of Conway's Game of Life on a 2D board using in-place state encoding — a direct parallel to how Roblox's voxel engine computes next-tick block states for physics simulations across large terrain grids.
- #1easyfoundational
1. Two Sum
Given an array of integers and a target, return the indices of two numbers that add up to the target.
- #2easyfoundational
2. Valid Parentheses
Determine if a string of brackets is properly opened and closed in the correct order.
- #3easyfoundational
3. Merge Two Sorted Lists
Merge two sorted linked lists into a single sorted linked list.
- #4easyfoundational
4. Remove Duplicates from Sorted Array
Remove duplicates from a sorted array in-place and return the new length.
- #5easyfoundational
5. Remove Element
Remove all occurrences of a target value from an array in-place.
- #6easyfoundational
6. Search Insert Position
Find the index where a target would be inserted in a sorted array.
- #7easyfoundational
7. Plus One
Increment a large integer represented as a digit array.
- #8easyfoundational
8. Merge Sorted Array
Merge two sorted arrays in-place into the first array.
- #9easyfoundational
9. Binary Tree Inorder Traversal
Return the in-order traversal of a binary tree's node values.
- #10easyfoundational
10. Same Tree
Check whether two binary trees are structurally identical with matching values.
- #11easyfoundational
11. Symmetric Tree
Check whether a binary tree is a mirror image of itself.
- #12easyfoundational
12. Maximum Depth of Binary Tree
Return the maximum depth of a binary tree.
- #13easyfoundational
13. Balanced Binary Tree
Determine if a binary tree is height-balanced.
- #14easyfoundational
14. Minimum Depth of Binary Tree
Find the shortest root-to-leaf path length.