Bit Manipulation - Single Number III (Two Singles)
Given the following code and input, what is the final returned list?
Given the following code and input, what is the final returned list?
easy🧾 Code Trace Q12 of Q15
Step-by-Step Solution
Step 1: Compute xor of all elements
xor = 2 ^ 4 ^ 2 ^ 5 = (2 ^ 2) ^ 4 ^ 5 = 0 ^ 4 ^ 5 = 1 (binary 0001)Step 2: Find rightmost set bit and partition
set_bit = xor & (-xor) = 1 & (-1) = 1. Partition nums by bit 1: group1 (bit set): 5, group2 (bit not set): 2,4,2. XOR group1 = 5, XOR group2 = 4.Final Answer:
Option C -> Option CQuick Check:
Output matches unique elements [OK]
Quick Trick: Rightmost set bit partitions unique numbers correctly [OK]
Common Mistakes:
MISTAKES- Mixing order of output
- Incorrect xor calculation
- Miscomputing set bit
Trap Explanation:
PITFALL- Candidates often confuse xor or set bit calculation leading to wrong partitioning.
Interviewer Note:
CONTEXT- Tests ability to trace bitwise XOR and partitioning logic precisely.
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