# Tag Info

## Hot answers tagged hashing

Accepted

### What exactly (and precisely) is "hash?"

The Wikipedia article on hash functions is very good, but I will here give my take. What is a hash? "Hash" is really a broad term with different formal meanings in different contexts. There ...
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### What exactly (and precisely) is "hash?"

A hash function is a function that takes an input and produces a value of fixed size. For example you might have a hash function stringHash that accepts a ...
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### Two-way Hash Functions

Yes, this is possible. Here are two examples of such a function. One function is $f(x)=x$. This has no collisions, and the function is easy to invert. Here is another function: define $f(x) = x$ ...
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### Hash functions and pathological data sets

An easy way to visualize this is to imagine a hash table of size $n$ (implemented with chaining) that contains all of the elements of $U$ (even though this is unrealistic in practice because $U$ ...
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### Understanding hashtable performance in the worst-case

The load factor denotes the average expected length of a chain, therefore it is interesting for an average case analysis, not the worst case analysis. That's why on average you expect needing constant ...

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### Hash function to hash 6-digit positive integers

I think you've missed the point of hash tables. Hash tables are used to give array-like access to a dataset that's too big and sparse to store in an array. So, for example, it sounds like you're ...
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### Given a string, is it possible to determine which hashing algorithm has produced it, if any?

You will first need to define what you mean by a hashing algorithm. For example, my favorite hashing algorithm is simple: check whether the input is "string", and if so, output "...
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### Given a string, is it possible to determine which hashing algorithm has produced it, if any?

No it is not possible to determine that is produced by a hashing algo, or which one that produced it -- at least not from a single sample. Good hashing algo will produce a uniform set of values ...
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### Two-way Hash Functions

In addition to everything that others have said: any cipher is an invertible "hash" function. And there are standard ways to construct them; one common way of turning a one-way function into an ...
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### Lemma 2 in Knuth's "Notes on Open Addressing"

I think that the notes have been reported incorrectly. Indeed CruiskeenLawn, you are right. I've found some very old notes here which report the correct result. Indeed, in your copy, they simply ...
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