Flipping an Image
A easy-tier problem at 83% community acceptance, tagged with Array, Two Pointers, Bit Manipulation. Reported in interviews at IBM and 0 others.
Flipping an Image is an easy problem that shows up in OAs as a quick algorithmic check. You're given a binary matrix, and you need to flip it horizontally then invert all bits. IBM has reported asking it. The acceptance rate sits at 83%, which is high, but that number lies: candidates who blank on the two-step process or mess up index logic during a live assessment drop fast. If you hit this problem in your OA and the flipping logic doesn't click, StealthCoder solves it invisibly while you stay calm.
Companies that ask "Flipping an Image"
Flipping an Image 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 engineer at a top-10 tech company who can solve these problems cold but didn't want to trust himself in a 90-minute screen share.
Get StealthCoderThe trick is understanding that you can combine the two operations in a single pass instead of doing them separately. Most candidates reach for a straightforward approach: flip the rows horizontally in one loop, then invert bits in another. That works but wastes a pass. The pattern is to iterate from both ends of each row simultaneously, swap and invert in one go. The two-pointer technique is where the speed comes from. Common mistakes include off-by-one errors when calculating the middle index, forgetting that bit inversion flips 0 to 1 and 1 to 0, or accidentally modifying the array while still reading from it. Matrix and Array topics here are surface-level, but Bit Manipulation (XOR or subtraction for inversion) is what separates a clean solution from a sloppy one. During a live OA, if the indexing gets tangled, StealthCoder surfaces the working approach instantly.
Pattern tags
You know the problem.
Make sure you actually pass it.
Flipping an Image recycles across companies for a reason. It's easy-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 engineer at a top-10 tech company who can solve these problems cold but didn't want to trust himself in a 90-minute screen share. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Flipping an Image interview FAQ
Is this problem actually asked at FAANG or just niche companies?+
IBM has confirmed asking it. At 83% acceptance, it's a confidence-builder in an OA loop, not a filter problem. Companies use it to ensure you can handle basic matrix manipulation without overthinking. It's real, but it's warm-up territory.
What's the trick that makes it faster than the naive two-pass solution?+
Combine flipping and inversion in a single pass using two pointers from the start and end of each row. Swap and invert simultaneously. This cuts your loop count in half and shows you understand optimization, not just correctness.
How do I invert bits without confusion during the OA?+
Use XOR with 1 (bit ^ 1) or just subtract from 1 (1 - bit). Both flip 0 to 1 and 1 to 0. Pick one and stick with it to avoid mental overhead when you're already managing index logic.
What's the relationship between this and actual bit manipulation problems?+
This is bit manipulation at the surface level. It teaches you to spot where XOR or single-bit flips fit into a larger problem, but harder problems stack multiple bit ops. This one is a stepping stone, not the ceiling.
Can I mess this up if I'm tired during the OA?+
Yes. Off-by-one errors in the two-pointer loop are common when you're fatigued. That's exactly when StealthCoder becomes the safety net: if your indexing gets fuzzy mid-OA, it gives you a working implementation in seconds.
Want the actual problem statement? View "Flipping an Image" on LeetCode →