A hash function is any algorithm that maps data of arbitrary length to data of a fixed length. The values returned by a hash function are called hash values, hash codes, hash sums, checksums or simply hashes. From Wikipedia: http://en.wikipedia.org/wiki/Hash_function
I was just wondering if there were some "standard" examples that everyone uses as a basis for explaining the nature of a problem that requires the use of a Hash table. What are some well-known ...
I've read a few times that when storing passwords, it's good practice to 'double hash' the strings (eg. with md5 then sha1, both with salts, obviously). I guess the first question is, "is this ...
I have undertaken a project concerning database deduplication. I did some research and have found that the Python dict type actually is a hashmap that uses open addressing. In the deduplication ...
Which is more efficient; which is faster? Trade-offs? Goal is for fast look-ups in a web application. UUIDs are the keys, so global will work. Approx 50 million values. A global cache is ...
TL;DR:what the title says I am developing some sort of image board in PHP. I was thinking of changing each image's filename to it's checksum prior to saving it. This way, I might be able to ...
I'm working on a system file scanner that reveals info about various files (e.g. size, last used, duplicates, etc). Currently I'm traversing the file system once just to get a good measure of the ...
I've been thinking about this problem recently and it really doesn't seem like it's possible, but I figured that I'd ask just in case. Assume a simple program, in pseudocode: run hash on an ...
Relevant XKCD There are many sites on the Internet that require login information, and the only way to protect against password reusing is the "promise" that the passwords are hashed on the server, ...
I want to understand the correct use and implementation of hash tables in php (sorry). I read somewhere that an in-experienced programmer created a hash table and then iterated through it. Now, I ...
When adding salt values to a hash value for something like a password that cannot be stored in plain text, what is the best place to get the salt values come from? For context, let us suppose this is ...
Which hashing algorithm is best for uniqueness and speed? Example (good) uses include hash dictionaries. I know there are things like SHA-256 and such, but these algorithms are designed to be ...
What is a good growth strategy for hash tables? If the number of elements exceeds the number of buckets, I increase the number of buckets with the following formula: n = int(n * 1.618033988749895) | ...