Diagonal Traverse
A medium-tier problem at 63% community acceptance, tagged with Array, Matrix, Simulation. Reported in interviews at Liftoff and 6 others.
Diagonal Traverse trips up candidates who think row-by-row or column-by-column. You get a 2D matrix and have to traverse it along diagonals, alternating direction each time you hit an edge. Liftoff, Nike, Meta, and Walmart Labs have all asked it. The acceptance rate sits at 63%, which means a third of people who attempt it get stuck on the direction-flip logic or boundary handling. If you blank on the traversal pattern during a live assessment, StealthCoder runs invisibly and surfaces a working solution in seconds.
Companies that ask "Diagonal Traverse"
Diagonal Traverse 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 trick is recognizing that diagonals move in two directions: up-right and down-left. Most candidates start coding a brute-force diagonal extractor and lose track of which direction they're in, or they hard-code boundary checks that miss edge cases. The real pattern is mathematical: as you move to the next diagonal, the sum of row and column indices changes predictably. You can iterate through diagonals by sum value, then sort or reverse each diagonal based on whether the sum is even or odd. Many fall into the trap of treating it as a simulation problem when it's really about understanding matrix geometry. When the obvious row-column iteration fails and you're stuck on the direction toggle, that's where preparation gaps show most. StealthCoder bridges that gap if the pattern doesn't click during the actual OA.
Pattern tags
You know the problem.
Make sure you actually pass it.
Diagonal Traverse 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.
Diagonal Traverse interview FAQ
Is this really asked at Meta and other big companies?+
Yes. Meta, Walmart Labs, Liftoff, and Roblox are all in the historical records. It's a medium that tests matrix navigation and simulation chops. Not a trick question by their standards, but you need to see the diagonal pattern quickly.
What's the main trap candidates fall into?+
Forgetting to reverse or flip direction on alternating diagonals. Most people write a loop that extracts diagonals but don't handle the alternating up-right and down-left pattern. Boundary logic gets messy fast without a clean mental model.
Does this problem actually test Algorithm or just Array manipulation?+
It tests both. The topics are Array, Matrix, and Simulation. You need to understand 2D indexing and implement a stateful traversal. It's not a hard algorithm, but the state machine aspect trips people up if they haven't done similar problems.
How long should this take in an interview if I know the trick?+
If you see the diagonal-sum pattern, 12 to 18 minutes for a clean solution and edge cases. Without the pattern, people often spend 30 plus minutes debugging direction flips and boundary conditions. The 63% acceptance rate reflects how many people don't nail it on first attempt.
Is there a mathematical shortcut, or do I need to simulate it?+
You can use the sum of indices (i plus j) to identify which diagonal a cell belongs to, then sort or reverse based on parity. This is more elegant than pure simulation and easier to debug. Simulation works too, but you're more prone to off-by-one errors on direction changes.
Want the actual problem statement? View "Diagonal Traverse" on LeetCode →