Domino and Tromino Tiling
A medium-tier problem at 52% community acceptance, tagged with Dynamic Programming. Reported in interviews at WinZO and 0 others.
Domino and Tromino Tiling is a medium-difficulty dynamic programming problem that shows up in live assessments when companies want to test whether you can recognize state transitions beyond the obvious. You're given an m x n board with one missing square, and you need to count ways to tile it with 1x2 dominoes and L-shaped trominoes. The acceptance rate sits around 52%, which means half the candidates who attempt it blank or overcomplicate it. If this problem hits your live OA and you haven't drilled the memoization pattern, StealthCoder surfaces a working solution in seconds, invisible to the proctor.
Companies that ask "Domino and Tromino Tiling"
Domino and Tromino Tiling is the kind of problem that decides whether you pass. StealthCoder reads the problem on screen and surfaces a working solution in under 2 seconds. Invisible to screen share. The proctor sees nothing. Built by an Amazon engineer who used it to pass JPMorgan's OA and system design loop.
Get StealthCoderThe trap here is trying to brute-force every possible tiling. The actual pattern is recognizing that this is a state-space search where you fill the board column by column (or row by row), tracking which cells are already occupied. You maintain a bitmask representing the 'profile' of the current boundary, recurse on next positions, and memoize on (position, mask). Most candidates either miss the bitmask optimization entirely, or they implement it but forget to handle the missing square constraint correctly. The insight is that dominoes and trominoes behave differently at the edges, so your state transition must account for both piece types and placement orientation. When you hit this live, the clock pressure makes the state design fragile. StealthCoder handles the memoization bookkeeping so you don't derail halfway through coding.
Pattern tags
You know the problem.
Make sure you actually pass it.
Domino and Tromino Tiling recycles across companies for a reason. It's medium-tier, and most candidates blank under the timer. StealthCoder is the hedge: an AI overlay invisible during screen share. It reads the problem and surfaces a working solution in under 2 seconds. Built by an Amazon engineer who used it to pass JPMorgan's OA and system design loop. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Domino and Tromino Tiling interview FAQ
Is Domino and Tromino Tiling still asked at real companies?+
Yes. WinZO has asked it. It's not a FAANG staple, but it appears in medium-tier tech OAs with regularity. The 52% acceptance rate suggests it's harder than typical medium problems, so if it shows up, you're being tested on your DP pattern recognition under time pressure.
What's the actual trick that most people miss?+
The trick is realizing you need a bitmask to represent which cells in the current column boundary are already filled by previous tiles. Candidates often try greedy or brute-force backtracking, which explodes in runtime. The bitmask DP collapses the state space dramatically.
How does this relate to other tiling problems?+
Tiling problems typically reduce to counting valid state transitions. This one is harder because you have two piece types (1x2 and L-shaped), so your fill logic must branch on piece choice. Standard domino-only problems are simpler; the tromino adds a second decision branch.
Can I solve this without bitmasks?+
Not efficiently for larger boards. Memoization without a compact state representation will either hit memory limits or time out. The bitmask is the canonical solution for profile-based DP on grid tiling.
How much time should I spend on this in an OA?+
If you recognize the bitmask DP pattern immediately, 20-30 minutes to code and debug. If you don't, you'll spin on brute-force for 45 minutes and run out of time. That's why knowing this pattern beforehand matters. StealthCoder is your safety net if you blank on the state design.
Want the actual problem statement? View "Domino and Tromino Tiling" on LeetCode →