fix: CompactDataBlock.n_tiles() missing paper's +3 term (#1943)

[kkoci]

Closes #1943.

Main's current n_tiles() computes ceil(1.5 * n_algo_qubits + 2). This differs from the cited paper (Litinski, arXiv:1808.02892, page 7, Fig. 9: "A compact block stores n data qubits in 1.5n+3 tiles") due to operator precedence ceil(1.5*n + 2) is not the same as ceil(1.5*(n+2)) for most n (e.g. n=2 gives 5 here, vs. the paper-correct 6).

This adds parentheses to match the paper: ceil(1.5 * (n_algo_qubits + 2)), algebraically 1.5n+3, matching the fix proposed and agreed on in the issue discussion.

Before: n_algo_qubits=2 -> 5 tiles
After: n_algo_qubits=2 -> 6 tiles (matches the paper)

Added a parametrized test in data_block_test.py (test_compact_block) covering n=2, 4, 100 against the paper-correct tile count.

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[gemini-code-assist]

Code Review

This pull request updates the n_tiles calculation in CompactDataBlock to add 2 to the number of algorithm qubits before performing the calculation. It also adds corresponding unit tests in data_block_test.py to verify this behavior. There are no review comments, so I have no feedback to provide.

[mpharrigan]

thanks!

[kkoci]

thanks!

The format check was still failing on your re-run because the code wasn't correctly formatted yet at that point, I'd fixed it locally since then. Just pushed the corrected version, black and ruff both confirm no formatting changes are needed on data_block.py or data_block_test.py now, so it should pass this time.