Number Complement
A easy-tier problem at 70% community acceptance, tagged with Bit Manipulation. Reported in interviews at Cloudera and 0 others.
Number Complement is an easy bit manipulation problem that shows up in real assessments despite its simplicity. Cloudera has asked it. The trick is dead straightforward once you see it, but candidates who haven't drilled bit operations often waste time converting to strings or overthinking the solution. If this problem hits your live OA and you blank on the bitwise approach, StealthCoder surfaces a working solution in seconds, invisible to the proctor. Seventy percent acceptance rate means it's winnable, but that remaining thirty percent are people who didn't nail the pattern before walking in.
Companies that ask "Number Complement"
Number Complement 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 because the OA filter rejects engineers who'd pass the on-site. That's a broken filter. This is the workaround.
Get StealthCoderThe core pattern: flip every bit in the number's binary representation. Most people's first instinct is to convert to a string, reverse it, swap 0s and 1s, then convert back. That works but it's slow and awkward. The real move is XOR. Once you know that XORing a number with a mask of all 1s (in the number's bit width) gives you the complement, the solution becomes a two-liner. The hard part is figuring out what that mask should be. Build it by finding the highest bit set in the original number, then creating a mask with all bits set up to that position. From there, XOR and you're done. StealthCoder handles the mask construction instantly if you freeze during the assessment.
Pattern tags
You know the problem.
Make sure you actually pass it.
Number Complement 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 because the OA filter rejects engineers who'd pass the on-site. That's a broken filter. This is the workaround. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Number Complement interview FAQ
Is this really asked at big companies?+
Yes. Cloudera has asked it. It's an easy problem, so it shows up as a warm-up or screening question, not a main-loop challenge. Don't sleep on it just because it's easy. Missing it in a live OA stings.
What's the most common wrong approach?+
Converting to a string, iterating through characters, flipping 0s and 1s, then converting back. It works but it's verbose and slow. Interviewers want to see you think in bitwise operations, not string manipulation. That's the tell.
How do I actually build the mask?+
Find the position of the highest set bit in your input number. Then create a mask where every bit up to and including that position is 1. For example, if your number is 5 (binary 101), the mask is 111 (7 in decimal). XOR the number with that mask and you get the complement.
Does bit manipulation show up in other easy problems?+
Frequently. If you're prepping for companies that ask Number Complement, you should also drill Hamming Distance, Single Number, and Reverse Bits. Bit Manipulation is a topic that's easy to avoid but hard to fake in an interview.
What if I get stuck during the live assessment?+
That's where StealthCoder wins. It reads the problem statement, recognizes the bit manipulation pattern, and surfaces the XOR-based solution instantly while your screen is shared. You paste it, walk through it, and move on without anyone knowing you hit a wall.
Want the actual problem statement? View "Number Complement" on LeetCode →