Rename hint.txt and hint.text to README.md
This commit is contained in:
Cody Boone Ferguson committed
1 parent
77fb0f11a2
commit
851e191519
166 files changed
No files matched your search
@@ -0,0 +1,160 @@
|
||||
# Most Different
|
||||
|
||||
Anthony Howe <achowe@snert.com>
|
||||
Montreal, Quebec, Canada
|
||||
<http://www.snert.com/>
|
||||
Twitter: @SirWumpus
|
||||
|
||||
|
||||
## Judges' comments:
|
||||
### To use:
|
||||
|
||||
make
|
||||
|
||||
./prog file1 file2
|
||||
|
||||
./prog -d file1 file2
|
||||
|
||||
### Try:
|
||||
|
||||
./prog prog.orig.c prog.c
|
||||
|
||||
make test
|
||||
./prog -d ABXYEFCD.tmp ACDBECFD.tmp
|
||||
./prog ABXYEFCD.tmp ACDBECFD.tmp
|
||||
|
||||
rm -f curds.tmp whey.tmp
|
||||
cp /usr/share/man/man1/cc.1 curds.tmp
|
||||
cp /usr/share/man/man1/cc.1 whey.tmp
|
||||
chmod 666 whey.tmp
|
||||
make makeholes
|
||||
./makeholes -n 1000 whey.tmp
|
||||
./prog curds.tmp whey.tmp
|
||||
./avgtime.sh 100 ./prog curds.tmp whey.tmp
|
||||
|
||||
# Assuming curl(1) installed, grab a really HUGE text file.
|
||||
curl -L -o war-and-peace.txt http://www.gutenberg.org/ebooks/2600.txt.utf-8
|
||||
cp war-and-peace.txt nuked.tmp
|
||||
./makeholes -c'~' -n 1000 nuked.tmp
|
||||
./prog war-and-peace.txt nuked.tmp
|
||||
./avgtime.sh 100 ./prog war-and-peace.txt nuked.tmp
|
||||
|
||||
### Selected Judges Remarks:
|
||||
|
||||
This is the best use of the FNV that we have seen in the IOCCC so far!
|
||||
The output, when used without -d, is compatible with POSIX diff and
|
||||
is suitable for use with patch.
|
||||
|
||||
We welcome back Canada to the list of nations from where winning
|
||||
entries have been submitted.
|
||||
|
||||
Is this code a bug or a feature? :-) Or is this an attempt to corrupt the
|
||||
programming of our youth? Should we heed Kyle's mom words that she uttered
|
||||
during a South Park P.T.A. Meeting?
|
||||
|
||||
"We must stop dirty (C) language from getting to our children's ears!"
|
||||
|
||||
[Blame Canada](https://www.youtube.com/watch?v=bOR38552MJA):
|
||||
|
||||
Or should we teach our youth to understand the intricacies of this code?
|
||||
Ying Tong Iddle I Po! We suggest you read the source for yourself, which
|
||||
might be easier than the academic papers it was inspired by.
|
||||
|
||||
NOTE: Unlike the original entry source, prog.orig.c, prog.c uses a
|
||||
64 bit FNV hash and fixes a function call warning.
|
||||
|
||||
## Author's comments:
|
||||
Features
|
||||
--------
|
||||
|
||||
* "An O(NP) Sequence Comparison Algorithm" by Wu, Manber, Myers, Miller.
|
||||
|
||||
* Output compatible with patch(1).
|
||||
|
||||
* Strokes one of the judge's ego (I couldn't email chocolate or curry).
|
||||
|
||||
|
||||
Description
|
||||
-----------
|
||||
|
||||
This is a functioning micro diff tool using an [O(NP) algorithm][Wu+89], compared to the older [O(ND) difference algorithm][Mye86] used by some versions of diff. Its output is based on the default diff(1) output described by POSIX and [The Open Group Base Specifications][SUSV7]. The output is suitable for use with patch(1).
|
||||
|
||||
The -d option simply writes the edit distance between file1 and file2.
|
||||
|
||||
|
||||
Observations
|
||||
------------
|
||||
|
||||
The FNV1a hash is a little slow compared to the trival hash GNU Diff uses. I downloaded a plain text copy of "War And Peace" from Project Gutenberg, used ``makeholes.c`` to make 1000 random changes, then profiled and timed the program verses GNU Diff. The bottle neck appears to be in the file I/O and line hashing with an average +0.05s slower. Using a huge file like "War And Peace" for testing offsets the diff(1) optimised file I/O.
|
||||
|
||||
There is no hash collision checking, partly because FNV1a appears to generate very [few collisions][HshCmp] and an assumption that localised collisions within a region of edits are highly unlikely.
|
||||
|
||||
|
||||
Support Files
|
||||
-------------
|
||||
|
||||
* ``prog-test.sh``
|
||||
Basic test program verifies known test edit distances and patch support.
|
||||
|
||||
* ``avgtime.sh``
|
||||
|
||||
* ``makeholes.c``
|
||||
Random edits (holes) made to a file in-place.
|
||||
|
||||
|
||||
References
|
||||
----------
|
||||
|
||||
Wu, Manber, Myers, and Miller; August 1989;
|
||||
"An O(NP) Sequence Comparison Algorithm";
|
||||
<http://myerslab.mpi-cbg.de/wp-content/uploads/2014/06/np_diff.pdf>
|
||||
|
||||
Fowler, Noll, Vo; 1994
|
||||
<http://www.isthe.com/chongo/tech/comp/fnv/index.html>
|
||||
|
||||
Fowler, Noll, Vo on Wikipedia
|
||||
<https://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function>
|
||||
|
||||
"diff", The Open Group Base Specifications Issue 7
|
||||
IEEE Std 1003.1, 2013 Edition
|
||||
<http://pubs.opengroup.org/onlinepubs/9699919799/utilities/diff.html>
|
||||
|
||||
Eugene W. Myers; "An O(ND) Difference Algorithm and Its Variations";
|
||||
Algorithmica, 1986, pages. 251-266
|
||||
<http://www.xmailserver.org/diff2.pdf>
|
||||
|
||||
Webb Miller and Eugene W. Myers; "A File Comparison Program";
|
||||
Software-Practice And Experience, Vol. 15(11). 1025-1040 (November 1985)
|
||||
<http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.189.70&rep=rep1&type=pdf>
|
||||
|
||||
D.S. Hirschberg, "A linear space algorithm for computing maximal common subsequence problem";
|
||||
Comm. of ACM, Vol. 18, June 1975, pages 341-343
|
||||
<http://www.mathcs.emory.edu/~cheung/Courses/323/Syllabus/DynProg/Docs/Hirschberg-LCS-1975.pdf>
|
||||
|
||||
Which hashing algorithm is best for uniqueness and speed?
|
||||
<http://programmers.stackexchange.com/questions/49550/which-hashing-algorithm-is-best-for-uniqueness-and-speed>
|
||||
|
||||
[Wu+89]: http://myerslab.mpi-cbg.de/wp-content/uploads/2014/06/np_diff.pdf
|
||||
|
||||
[FNV94]: http://www.isthe.com/chongo/tech/comp/fnv/index.html
|
||||
|
||||
[FNVWi]: https://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function
|
||||
|
||||
[Mye86]: http://www.xmailserver.org/diff2.pdf
|
||||
|
||||
[SUSV7]: http://pubs.opengroup.org/onlinepubs/9699919799/utilities/diff.html
|
||||
|
||||
[Mil85]: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.189.70&rep=rep1&type=pdf
|
||||
|
||||
[Hir75]: http://www.mathcs.emory.edu/~cheung/Courses/323/Syllabus/DynProg/Docs/Hirschberg-LCS-1975.pdf
|
||||
|
||||
[HshCmp]: http://programmers.stackexchange.com/questions/49550/which-hashing-algorithm-is-best-for-uniqueness-and-speed
|
||||
|
||||
--------------------------------------------------------------------------------
|
||||
<!--
|
||||
(c) Copyright 1984-2016, [Leo Broukhis, Simon Cooper, Landon Curt Noll][judges] - All rights reserved
|
||||
This work is licensed under a [Creative Commons Attribution-ShareAlike 3.0 Unported License][cc].
|
||||
|
||||
[judges]: http://www.ioccc.org/judges.html
|
||||
[cc]: http://creativecommons.org/licenses/by-sa/3.0/
|
||||
-->
|
||||
Reference in new issue
Block a user