Advanced~2h
Bit Manipulation in Data Structures & AlgorithmsInterview Readiness Check
XOR tricks, bitmasks, counting bits — power of 2, single number, counting bits.
XORbitmaskAND OR NOTleft shiftsingle numberpower of twocounting bits
Learning path
Try a sample question
Find the single number in an array where every element appears twice except one (e.g. [2,2,1,3,3] → 1). Which bit trick solves this in O(n) time, O(1) space?
A.Sort the array and scan for the element without a pair
B.Use a HashSet: add elements not in set, remove elements already in set
C.XOR all elements: a XOR a = 0, a XOR 0 = a. All pairs cancel to 0; the single number remains.
D.Sum all elements, subtract sum of unique elements × 2
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What this module tests
- Conceptual understanding of bit manipulation fundamentals
- Trade-offs and design decisions in real system scenarios
- XOR and bitmask — applied knowledge
- Interview-style reasoning and explanation quality
Free to start
Take the Bit Manipulation check →
10 questions · Dimension scoring · AI coach feedback · Shareable result
Test your knowledge — free →No credit card · Takes 10–15 min
Frequently asked questions
- What does the Bit Manipulation check test?
- The check covers xor tricks, bitmasks, counting bits — power of 2, single number, counting bits. Questions span beginner to advanced difficulty and test both conceptual understanding and practical trade-off reasoning.
- What keywords should I know for Bit Manipulation?
- Key concepts include: XOR, bitmask, AND OR NOT, left shift, single number, power of two, counting bits. These frequently appear in data structures & algorithms interviews at product and infrastructure companies.
- How many questions are in the check?
- Each check has 10 questions — a mix of MCQ and short-answer. You get scored by dimension (e.g., scalability, consistency) so you know exactly where to focus.
- How long does it take to study Bit Manipulation?
- Most engineers spend around 2 hours on this module. The check itself takes about 10–15 minutes. You can retake it up to 3 times per day.
- What prerequisite knowledge do I need before Bit Manipulation?
- Bit Manipulation builds on Arrays & Hashing. Complete those first for the best results.
- Is XOR, bitmask, AND OR NOT covered?
- Yes. The Bit Manipulation module covers XOR, bitmask, AND OR NOT among other key concepts. The check includes questions that reflect real data structures & algorithms interview patterns.