Find the Solo Sensor Reading
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Find the Solo Sensor Reading
A sorted sensor log contains duplicate readings from paired devices. Exactly one reading was produced by a solo device and appears only once. Every other reading appears exactly twice, and equal readings are adjacent because the log is sorted. Find the solo reading. The returned value must be the reading itself, not its position. The input is guaranteed to follow the pairing rule, so exactly one answer exists. Input Format: You are given a sorted integer array readings. Output Format: Return the single value that appears exactly once.
Examples
readings = [1, 1, 2, 3, 3, 4, 4, 8, 8]
2
Explanation: All readings are paired except value 2 at index 2. The pair pattern breaks there, so that value is returned.
Approach hint
Look at the index where each pair starts before and after the single value.
Common mistake
Skipping assumptions, edge cases, or trade-offs can make an otherwise good answer feel incomplete.