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So I'm reading up about hash tables, hash functions etc. I was intrigued to read on wikipedia about how "dynamic perfect hashing" involves using a second hash table as the data structure to store multiple values within a particular bucket.
Where I get...
Started by Arj on
, 3 posts
by 3 people.
Answer Snippets (Read the full thread at stackoverflow):
To make insertion....
For inserting amortized).
The hash function for the second level tables are chosen at random: Hashing
Perfect hashing means that read access takes constant time even in the worst case.
Tables are still small.
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Is hashing a password twice before storage any more or less secure than just hashing it once?
What I'm talking about is doing this:
$hashed_password = md5( md5( plaintext_password ) );
instead of just this:
$hashed_password = md5( plaintext_password )...
Started by Bill the Lizard on
, 12 posts
by 12 people.
Answer Snippets (Read the full thread at stackoverflow):
Double hashing likely to contain the "password....
This increases the time it takes for an attacker to try each password a modern cryptographic hash such as the SHA-2 family (SHA-256, SHA-384, and SHA-512).
Of the hash function.
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Hi all
I know that Java has beautiful inbuilt support for the HashMaps or HashTables.
Does anybody have knowledge that what kind of hashing functions or techniques are employed by Java language?
Is it possible to tweak those functions to be able to make...
Started by shuby_rocks on
, 9 posts
by 9 people.
Answer Snippets (Read the full thread at stackoverflow):
Override String (you can't), in practice, it's hash function is practically always "good enough tend to have zeroes in their lower bits-- there's generally no practical hash function Classes to use a hashing algorithm....
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Ask your Facebook Friends
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I have lots of unrelated named things that I'd like to do quick searches against. An "aardvark" is always an "aardvark" everywhere, so hashing the string and reusing the integer would work well to speed up comparisons. The entire set of names is unknown...
Started by Jason Citron on
, 13 posts
by 13 people.
Answer Snippets (Read the full thread at stackoverflow):
Cheers,
Carl
The Hsieh hash function is pretty good, and has some benchmarks....
That topic has been discussed before:
http://stackoverflow.com/questions/98153/
Murmur Hash works well, but it won't be an alphabetic sort).
function.
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I'm writing a program right now which produces four unsigned 32-bit integers as output from a certain function. I'm wanting to hash these four integers, so I can compare the output of this function to future outputs.
I'm having trouble writing a decent...
Started by GenTiradentes on
, 9 posts
by 9 people.
Answer Snippets (Read the full thread at stackoverflow):
If you....
Why a hash? It seems like a std all.
This will be faster and will ensure no collisions.
Here's a fairly reasonable hash function from 4 integers to 1 integer than hashing.
With a good hashing function.
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I'm currently using this code for md5 hashing in Delphi 7:
function MD5(const fileName : string) : string; var idmd5 : TIdHashMessageDigest5; fs : TFileStream; begin idmd5 := TIdHashMessageDigest5.Create; fs := TFileStream.Create(fileName, fmOpenRead ...
Started by Mikey on
, 3 posts
by 3 people.
Answer Snippets (Read the full thread at stackoverflow):
Compare your results with:
md5(file_get_contents( )) in PHP
hash("md5", ) from the PHP hash framework extension
the command line programs md5(1) aka md5sum(1)
If all but one.
To check out this article.
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Is there a (Well known) hash function for string s which can be computed from hashes of subsets of s. e.g.
hash(0 to x) is hash(0 to x/2) + hash(x/2 to x) // plus or any other mathematical operation
Started by hasanatkazmi on
, 4 posts
by 4 people.
Answer Snippets (Read the full thread at stackoverflow):
You can construct a hash tree with any hashing function be considered a rather poor hash with regards to various characteristics of a hash function....
Which is bad for a hash function.
Constructing ...
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I've found the standard hashing function on VS2005 is painfully slow when trying to achieve high performance look ups. What are some good examples of fast and efficient hashing algorithms that should void most collisions?
Started by PiNoYBoY82 on
, 9 posts
by 9 people.
Answer Snippets (Read the full thread at stackoverflow):
However, they generally require that the....
Edit: Almost forgot: This page has a nice hash-function shootout, the best hash function is often a perfect hash function .
Implementations are easy to find on the net.
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How does the process of hashing work in Dictionary? I read that using dictionary provides faster look up. But did not understand how? How does the hashing and mapping to an index happen? Couldn't find any good reference.
EDIT: How is the actual memory...
Started by n0vic3c0d3r on
, 6 posts
by 6 people.
Answer Snippets (Read the full thread at stackoverflow):
This does work faster than searching a list always faster than searching... .
This hashing function is almostBy using a Computer Science concept called a Hash Map .
Instead the key is " hashed ", and used as an index into a list.
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Hello,
I am facing an application that uses hashing, but I cannot still figure out how it works. Here is my problem, hashing is used to generate some index, and with those indexes I access to different tables, and after I add the value of every table ...
Started by Eduardo on
, 5 posts
by 5 people.
Answer Snippets (Read the full thread at stackoverflow):
Hash implementations are used for processing efficiency, as they'll provide youIs it a bloom filter....
Hashing the point of hashing.
The hash of what you are keying off of, which is then used as an index into a data structure.
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