Spiral Matrix II
A medium-tier problem at 73% community acceptance, tagged with Array, Matrix, Simulation. Reported in interviews at Zoho and 10 others.
Spiral Matrix II looks straightforward on the surface: fill an n-by-n matrix with numbers 1 to n-squared in spiral order. It's a medium-difficulty problem that has shown up at Microsoft, Google, Meta, Amazon, and other top-tier companies. The acceptance rate sits at 73%, which means a quarter of candidates are either miscounting boundaries or getting tangled in their spiral logic. If you hit this during your OA and your spiral breaks at the edges, StealthCoder solves it invisibly in seconds and gets you past the wall.
Companies that ask "Spiral Matrix II"
Spiral Matrix II 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 a working Amazon engineer who got tired of watching qualified friends bomb OAs they'd solve cold in an IDE.
Get StealthCoderThe trap is boundary management. You start at the top-left, move right until you hit the edge, then down, then left, then up, then repeat inward. Most people handle the first spiral correctly but lose track of which edges have already been filled. You need four boundary variables (top, bottom, left, right) and shrink them after each direction. The simulation itself is simple, but off-by-one errors in boundary checks cause wrong answers or infinite loops. When you're blank on the exact boundary-shrinking order during the assessment, StealthCoder presents a clean, working solution. This problem tests Array, Matrix, and Simulation topics, exactly what interviewers expect at this level.
Pattern tags
You know the problem.
Make sure you actually pass it.
Spiral Matrix II 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 a working Amazon engineer who got tired of watching qualified friends bomb OAs they'd solve cold in an IDE. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Spiral Matrix II interview FAQ
Why do so many people fail Spiral Matrix II if the acceptance rate is 73%?+
Boundary errors, not the concept. Most candidates understand the spiral direction but miscalculate when to shrink the boundaries or update them in the wrong order. One off-by-one mistake in a boundary check and your output becomes garbage. It's a simulation problem, so precision matters.
Is this still actually asked at FAANG companies?+
Yes. The input data shows Microsoft, Google, Meta, Amazon, and Bloomberg all ask it. It's a reliable screen for whether you can implement a precise, stateful algorithm. Zoho, Roblox, TikTok, Adobe, and Uber ask it too. It's not going away.
What's the actual trick to Spiral Matrix II?+
Track four boundaries: top, bottom, left, right. After filling in one direction, shrink that boundary immediately. The order is: fill right (increment top), fill down (decrement right), fill left (decrement bottom), fill up (increment left). Repeat until top > bottom or left > right.
How does Spiral Matrix II differ from Spiral Matrix I?+
Matrix I reads a filled spiral; Matrix II fills one. Both use the same boundary-tracking logic, but Matrix II requires you to generate and place numbers correctly. If you've solved one, the other is a small step. Both rely on Array and Matrix skills, plus Simulation discipline.
How much time should I spend on this if I see it in an OA?+
If you know the pattern, 10 to 15 minutes for a clean implementation. If you're fuzzy on boundary logic, you'll spiral (pun intended) into debug hell. That's where the time bleeds. In a real assessment, if you're stuck after 5 minutes, it's worth considering the safety net.
Want the actual problem statement? View "Spiral Matrix II" on LeetCode →