mirror of https://github.com/python/cpython
bf121d6a69
* GH-116554: Relax list.sort()'s notion of "descending" run Rewrote `count_run()` so that sub-runs of equal elements no longer end a descending run. Both ascending and descending runs can have arbitrarily many sub-runs of arbitrarily many equal elements now. This is tricky, because we only use ``<`` comparisons, so checking for equality doesn't come "for free". Surprisingly, it turned out there's a very cheap (one comparison) way to determine whether an ascending run consisted of all-equal elements. That sealed the deal. In addition, after a descending run is reversed in-place, we now go on to see whether it can be extended by an ascending run that just happens to be adjacent. This succeeds in finding at least one additional element to append about half the time, and so appears to more than repay its cost (the savings come from getting to skip a binary search, when a short run is artificially forced to length MIINRUN later, for each new element `count_run()` can add to the initial run). While these have been in the back of my mind for years, a question on StackOverflow pushed it to action: https://stackoverflow.com/questions/78108792/ They were wondering why it took about 4x longer to sort a list like: [999_999, 999_999, ..., 2, 2, 1, 1, 0, 0] than "similar" lists. Of course that runs very much faster after this patch. Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com> Co-authored-by: Pieter Eendebak <pieter.eendebak@gmail.com> |
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| ACKS | ||
| HISTORY | ||
| Porting | ||
| README | ||
| README.AIX | ||
| README.coverity | ||
| README.valgrind | ||
| SpecialBuilds.txt | ||
| coverity_model.c | ||
| externals.spdx.json | ||
| indent.pro | ||
| platform_triplet.c | ||
| python-config.in | ||
| python-config.sh.in | ||
| python-embed.pc.in | ||
| python.man | ||
| python.pc.in | ||
| sbom.spdx.json | ||
| stable_abi.toml | ||
| svnmap.txt | ||
| valgrind-python.supp | ||
| vgrindefs | ||
README
Python Misc subdirectory
========================
This directory contains files that wouldn't fit in elsewhere. Some
documents are only of historic importance.
Files found here
----------------
ACKS Acknowledgements
HISTORY News from previous releases -- oldest last
indent.pro GNU indent profile approximating my C style
NEWS News for this release (for some meaning of "this")
Porting Mini-FAQ on porting to new platforms
python-config.in Python script template for python-config
python.man UNIX man page for the python interpreter
python.pc.in Package configuration info template for pkg-config
README The file you're reading now
README.AIX Information about using Python on AIX
README.coverity Information about running Coverity's Prevent on Python
README.valgrind Information for Valgrind users, see valgrind-python.supp
SpecialBuilds.txt Describes extra symbols you can set for debug builds
svnmap.txt Map of old SVN revs and branches to hg changeset ids,
help history-digging
valgrind-python.supp Valgrind suppression file, see README.valgrind
vgrindefs Python configuration for vgrind (a generic pretty printer)