Use perfect hash for temperature lookup

[ianopolousfast]

Check List:

• You have run ./mvnw verify and the project builds successfully
• Tests pass (./test.sh <username> shows no differences between expected and actual outputs)
• All formatting changes by the build are committed
• Your launch script is named calculate_average_<username>.sh (make sure to match casing of your GH user name) and is executable
• Output matches that of calculate_average_baseline.sh
• For new entries, or after substantial changes: When implementing custom hash structures, please point to where you deal with hash collisions (line number)

• Execution time: 11.4s on 4 core i7 (.6s faster)
• Execution time of reference implementation: 288s

[gunnarmorling]

Coming in a bit slower than before:

Benchmark 1: timeout -v 300 ./calculate_average_ianopolousfast.sh 2>&1
  Time (mean ± σ):      4.781 s ±  0.061 s    [User: 33.966 s, System: 0.747 s]
  Range (min … max):    4.695 s …  4.847 s    5 runs

Summary
  ianopolousfast: trimmed mean 4.787922194599999, raw times 4.6949676626,4.742957694599999,4.8201604766,4.8006484126,4.8468138546

Leaderboard

| # | Result (m:s.ms) | Implementation     | JDK | Submitter     | Notes     |
|---|-----------------|--------------------|-----|---------------|-----------|
|   | 00:04.787 | [link](https://github.com/gunnarmorling/1brc/blob/main/src/main/java/dev/morling/onebrc/CalculateAverage_ianopolousfast.java)| 21.0.1-open | [Dr Ian Preston](https://github.com/ianopolousfast) |  |

[ianopolousfast]

That's puzzling. It was a big speed up locally on 4 and 12 core machines.

[gunnarmorling]

Just ran it again, same outcome (within the precision I can measure, it fluctuates by +- 1.5%).