Check if There is a Valid Path in a Grid
A medium-tier problem at 49% community acceptance, tagged with Array, Depth-First Search, Breadth-First Search. Reported in interviews at Robinhood and 0 others.
You're looking at a grid navigation problem that Robinhood asks. It's medium difficulty with a 49% acceptance rate, meaning half the people who attempt it walk away empty-handed. The trap is that naive pathfinding doesn't work here because the grid contains directional pipes, and you need to validate that each connection actually lines up. Most candidates start with standard DFS or BFS and only realize mid-interview that they forgot to check if the pipes are compatible. If this hits your live OA and you blank on the validation logic, StealthCoder solves it in seconds, invisible to the proctor.
Companies that ask "Check if There is a Valid Path in a Grid"
Check if There is a Valid Path in a Grid 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. Made by an Amazon engineer who watched the leaked-problem repo become an industry secret. He decided you should have it too.
Get StealthCoderThe core trick is that you can't just check if a neighbor exists. You need to verify that the pipe segments actually connect. Each cell contains a specific pipe type (horizontal, vertical, bend, T-junction, cross) with defined exit points. When you move from one cell to another, the entering direction must match the pipe's geometry, and the exiting direction must too. Most candidates implement DFS or BFS fine but skip the pipe-matching validation, which tanks their solution. Union Find can also work, but it requires the same validation logic underneath. The pattern is direction tracking plus explicit connection checking. This is where the 51% failure rate lives. StealthCoder is the hedge when you hit this problem live and the validation rules aren't clicking in real time.
Pattern tags
You know the problem.
Make sure you actually pass it.
Check if There is a Valid Path in a Grid 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. Made by an Amazon engineer who watched the leaked-problem repo become an industry secret. He decided you should have it too. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Check if There is a Valid Path in a Grid interview FAQ
Is this really a medium? It feels harder.+
The 49% acceptance rate says it's calibrated correctly for medium, but the catch is that validation logic isn't intuitive. Most people implement pathfinding correctly but forget to check that pipes actually connect directionally. That one detail drops pass rates hard.
DFS or BFS? Does it matter?+
Both work. DFS and BFS are interchangeable here because you're just exploring connected paths, not optimizing for distance or speed. The actual difficulty is the pipe-validation logic, not the traversal strategy. Pick whichever you're faster with.
Can I use Union Find?+
Union Find solves the connectivity problem, yes. But you still need to validate pipe connections before merging. It's not faster than DFS/BFS and adds complexity. Most people are faster with simple graph traversal.
Does Robinhood really ask this often?+
It's in their reported asks, but lower frequency than common problems like merge intervals or two sum variants. If you're prepping for Robinhood, know this pattern but don't spend all week on it. Build confidence on the higher-frequency problems first.
What's the gotcha I should drill?+
The direction-validation step. Before you visit a neighbor, check that the current pipe exits in that direction AND the neighbor's pipe enters from that direction. Skipping this check is the #1 reason solutions fail. Drill that logic until it's automatic.
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