Asteroid Collision
A medium-tier problem at 46% community acceptance, tagged with Array, Stack, Simulation. Reported in interviews at Qualtrics and 23 others.
Asteroid Collision is a medium-difficulty array problem that shows up across 24+ companies, including Qualtrics, SoFi, Roku, and Flipkart. You're given asteroids moving in a line, each with a size and direction. When two collide, the smaller explodes; if equal, both explode; if one's moving away, they don't collide. The 45% acceptance rate tells you most candidates miss the state-management piece. The trap is trying to simulate collisions naively. You need to track direction and handle chain reactions. If this problem catches you mid-OA without the stack pattern fresh, StealthCoder surfaces the solution invisibly while you stay calm.
Companies that ask "Asteroid Collision"
Asteroid Collision 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 algorithmic trick is recognizing this as a Stack problem, not just an array problem. You iterate through asteroids and push them onto a stack, but before you do, you simulate collisions with the top of the stack. The key insight: asteroids moving right (positive direction) are 'pending' until they meet asteroids moving left (negative). Those left-moving asteroids check the stack in order. If a pending right-mover is smaller, it explodes and you pop the stack. If larger, you pop and keep checking. If equal, both explode. The obvious mistake is trying to simulate two-pointer or index-based collision tracking, which gets messy with explosions. Stack handles the chain-reaction nature cleanly. When the pattern clicks, the code is short and clear. If you blank on it during the live assessment, StealthCoder reads your problem and delivers the stack-based approach in seconds, keeping you in control.
Pattern tags
You know the problem.
Make sure you actually pass it.
Asteroid Collision 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.
Asteroid Collision interview FAQ
Is Asteroid Collision still asked at major companies?+
Yes. It appears across 24+ companies including Qualtrics, SoFi, Roku, and Flipkart. It's not a rare edge case. You'll see it in assessments for fintech (SoFi, IMC), media (Roku, Zynga), and commerce (Flipkart, Myntra). Expect it to stay in rotation.
What's the actual trick everyone misses?+
Treating it as a stack problem instead of a simulation problem. Candidates often try two-pointer or index-tracking, which breaks down when asteroids explode. The stack handles collision chains naturally. Once you see it, the problem shrinks from 'complex' to 'obvious'.
Why is the acceptance rate only 45%?+
Because the state-management is non-obvious. You have to track direction, size, and the fact that one collision can trigger another. Without the stack pattern, you end up over-engineering or missing edge cases like chain explosions.
How does this relate to the other topics, Array and Simulation?+
Array is the input format. Simulation is the intuition you start with. But the actual solution uses Stack to manage the collision sequence cleanly. Many medium problems sit at this intersection where your first instinct is wrong and you need a structural shift.
How much time should I spend drilling this before an OA?+
One solid pass to understand the stack pattern and trace a few examples. If it hits your live assessment and you blank, that's why StealthCoder exists. It's the hedge for the one problem you didn't nail in prep.
Want the actual problem statement? View "Asteroid Collision" on LeetCode →