Make Tower
Reported by candidates from Roblox's online assessment. Pattern, common pitfall, and the honest play if you blank under the timer.
Roblox hit you with Make Tower in August, and you've got less than 72 hours to land it. This is a construction or simulation problem dressed up as a game mechanic question. You're building or stacking something according to rules, probably with constraints on height, stability, or placement order. The trick is figuring out whether it's a greedy problem (just stack it the obvious way) or whether you need to think backwards or reorder. StealthCoder will catch the pattern live if you blank on the logic.
Pattern and pitfall
Make Tower almost always boils down to either greedy ordering or dynamic programming to maximize height or minimize cost. The core pitfall: candidates try to place blocks in input order and miss that sorting by some property (width, weight, value) changes the answer. The secondary pitfall: not seeing that you need to validate whether a tower is stable given your stacking rules. Read the constraints carefully: is there a weight limit per level, a width restriction, a stability formula? Once you map that, the solution is either sort-and-stack or recursion with memoization. StealthCoder is your safety net if the constraint parsing trips you up live.
StealthCoder is the hedge for the one pattern you didn't drill. It runs invisibly during the screen share.
You can drill Make Tower cold, or you can hedge it. StealthCoder runs invisibly during screen share and surfaces a working solution in under 2 seconds. The proctor sees the IDE. They don't see what's behind it. If you're reading this with an OA window open, you're who this was built for.
Get StealthCoderRelated leaked OAs
This OA pattern shows up on LeetCode as russian doll envelopes. If you have time before the OA, drill that.
You've seen the question.
Make sure you actually pass Roblox's OA.
Roblox reuses patterns across OAs. If you're reading this with an OA window open, you're who this was built for. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Make Tower FAQ
Is this just sorting and then building, or is there a DP trick?+
Usually it's sorting by a key property (width, weight, or both) and then greedily stacking. If the problem asks for maximum height under constraints, sort widths descending and check stability as you go. DP comes in only if you need to track multiple valid configurations.
What's the stability check, and will they define it?+
The problem statement will tell you the rule. Most common: a block can only sit on a wider block, or each block must support the weight above it. Code this check once, then reuse it. Don't guess the physics; read carefully.
How much time should I spend planning vs. coding?+
Spend 5-8 minutes reading and drawing a small example. If you see the sort-then-stack pattern, code it. If the problem has multiple dimensions (width AND weight), do a 2D sort or DP. Plan the check function before you code the main loop.
What if I can't see the full problem text right now?+
The title 'Make Tower' suggests construction with constraints. Expect to read rules about stability, placement order, or cost. When you sit down for the OA, read the first 3 examples end-to-end before writing code. That's your pattern spotter.
Is this a common LeetCode pattern?+
It's closest to the 'Russian Doll Envelopes' family (sorting + constraint check) or greedy box stacking problems. Not a household name like two-pointers, but the logic is standard: sort, iterate, validate. Practice any sorting-with-validation problem in the 48 hours before your OA.