Which approach guarantees the most optimal and constant-time solution for this problem?
easy🔍 Pattern Recognition Q11 of Q15
Bit Manipulation - Reverse Bits
You are given a 32-bit unsigned integer and need to produce another 32-bit unsigned integer where the bits are reversed in order (the least significant bit becomes the most significant bit, and so on). Which approach guarantees the most optimal and constant-time solution for this problem?
ABrute force bit-by-bit reversal using a loop that processes each bit sequentially.
BBit manipulation using divide and conquer masks that swap bits in pairs, then nibbles, then bytes, etc.
CDynamic programming to store intermediate reversed results for subproblems of smaller bit lengths.
DGreedy approach that swaps bits whenever a mismatch is found scanning from both ends.
Step-by-Step Solution
Solution:
Step 1: Understand problem constraints
The problem requires reversing bits in a fixed 32-bit integer efficiently.
Step 2: Identify optimal approach
Bit manipulation with divide and conquer masks swaps bits in groups (pairs, nibbles, bytes) in constant time, achieving O(1) complexity.
Final Answer:
Option B -> Option B
Quick Check:
Divide and conquer bit swaps guarantee constant time reversal [OK]
Quick Trick:Divide and conquer bit swaps yield O(1) time reversal [OK]
Common Mistakes:
MISTAKES
Assuming brute force is optimal despite O(32) time
Confusing greedy swaps with guaranteed correctness
Thinking DP applies to bit reversal
Trap Explanation:
PITFALL
Brute force looks straightforward and correct but is O(32), not constant; greedy swaps may miss bits; DP is unrelated here.
Interviewer Note:
CONTEXT
Tests if candidate can recognize bit manipulation patterns beyond naive loops.
Master "Reverse Bits" in Bit Manipulation
3 interactive learning modes - each teaches the same concept differently
