Commit Graph

16 Commits

Author SHA1 Message Date
kleines Filmröllchen
b81a457de5 AK: Change quicksort comments to standard // style 2022-12-12 15:03:57 +00:00
Marc Luqué
22f472249d AK: Introduce cutoff to insertion sort for Quicksort
Implement insertion sort in AK. The cutoff value 7 is a magic number
here, values [5, 15] should work well. Main idea of the cutoff is to
reduce recursion performed by quicksort to speed up sorting
of small partitions.
2022-12-12 15:03:57 +00:00
Andreas Kling
ae3ffdd521 AK: Make it possible to not using AK classes into the global namespace
This patch adds the `USING_AK_GLOBALLY` macro which is enabled by
default, but can be overridden by build flags.

This is a step towards integrating Jakt and AK types.
2022-11-26 15:51:34 +01:00
Mart G
c9f3cc6dcc AK: Guarantee a maximum stack depth for dual_pivot_quick_sort
When the two chosen pivots happen to be the smallest and largest
elements of the array, three partitions will be created, two of
size 0 and one of size n-2. If this happens on each recursive call
to dual_pivot_quick_sort, the stack depth will reach approximately n/2.

To avoid the stack from deepening, iteration can be used for the
largest of the three partitions. This ensures the stack depth
will only increase for partitions of size n/2 or smaller, which
results in a maximum stack depth of log(n).
2021-04-28 21:38:48 +02:00
Mart G
67b0d04315 AK: Change pivot selection of dual_pivot_quick_sort
Picking the first and last elements as pivots makes it so that
a sorted array is the worst-case input for the algorithm.

This change instead picks pivots at approximately 1/3 and 2/3 in
the array. This results in desired performance for sorted arrays.

Of course this only changes which inputs result in worst-case
performance, but hopefully those inputs occur less frequently than
already sorted arrays.
2021-04-28 21:38:48 +02:00
Brian Gianforcaro
1682f0b760 Everything: Move to SPDX license identifiers in all files.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.

See: https://spdx.dev/resources/use/#identifiers

This was done with the `ambr` search and replace tool.

 ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
2021-04-22 11:22:27 +02:00
Mart G
9068398f6b AK: Make single pivot quick_sort guarantee a max stack depth of log(n)
- The change to quick_sort requires SimpleIterator to support
  assignment.
- Rename quick_sort to single_pivot_quick_sort to make it easier
  to choose a specific implementation (not based on signature).
- Ensure single_pivot_quick_sort does not copy the pivots
- Expand sorts_without_copy test case to cover both single and dual
  pivot implementations.
2021-02-01 09:52:36 +01:00
AnotherTest
ec4980e875 AK: Ensure dual_pivot_quick_sort does not copy the pivots
Also add a test that would fail to compile if quick_sort tries to copy
anything :P
2020-12-10 11:02:02 +01:00
wilsonk
75f6454de7
AK: Dual pivot quicksort implementation (#1838) 2020-04-18 13:58:49 +02:00
Andreas Kling
686ade6b5a AK: Make quick_sort() a little more ergonomic
Now it actually defaults to "a < b" comparison, instead of forcing you
to provide a trivial less-than comparator. Also you can pass in any
collection type that has .begin() and .end() and we'll sort it for you.
2020-03-03 16:02:58 +01:00
Andreas Kling
94ca55cefd Meta: Add license header to source files
As suggested by Joshua, this commit adds the 2-clause BSD license as a
comment block to the top of every source file.

For the first pass, I've just added myself for simplicity. I encourage
everyone to add themselves as copyright holders of any file they've
added or modified in some significant way. If I've added myself in
error somewhere, feel free to replace it with the appropriate copyright
holder instead.

Going forward, all new source files should include a license header.
2020-01-18 09:45:54 +01:00
Andreas Kling
7ad8790d80 LibGUI: Run clang-format on everything. 2019-06-07 11:46:02 +02:00
Robin Burchell
0dc9af5f7e Add clang-format file
Also run it across the whole tree to get everything using the One True Style.
We don't yet run this in an automated fashion as it's a little slow, but
there is a snippet to do so in makeall.sh.
2019-05-28 17:31:20 +02:00
Robin Burchell
23a5ce3319 QuickSort: Don't sort a single item, nothing to do 2019-05-26 01:47:41 +02:00
Andreas Kling
6e305bf838 AK: Simplify quick_sort() and improve Vector iterators a bit. 2019-05-19 01:53:51 +02:00
Andreas Kling
0d5e6593b2 AK: Add a basic QuickSort template implementation.
It was depressing not being able to capture anything when passing a lambda
to qsort_r() so let's just have our own QuickSort. I was gonna have to do
this eventually anyway. :^)
2019-03-09 16:20:12 +01:00