# [−][src]Crate hashed_permutation

This crate implements an algorithm that performs zero-cost permutations and shuffling on a range of numbers.

This method, discovered by Andrew Kensler in 2013, uses bit-twiddling to permute a range of
numbers, from `[0..n)`

without needing to mutate state or store the whole range of numbers. It
is extremely efficient, with no memory overhead (i.e. you don't have to store the whole range
of numbers).

This is effectively the same as taking some vector of numbers from `[0..n)`

, randomly shuffling
each element, and then calling the nth index of that vector. Kensler's algorithm offers a way
to achieve the same effect, except we don't need to store a whole vector for that range of
numbers.

# Example Usage

Using this library is fairly simple:

use std::num::NonZeroU32; let perm = HashedPermutation { seed: 1234, length: NonZeroU32::new(10).unwrap(), }; // Let's pick a randomly permuted number let permuted_number = perm.shuffle(0).unwrap();

## Iterators

You can also use this structure as an iterator to iterate through a permuted set from `(0..n)`

.

use std::num::NonZeroU32; // Loop from (0..10) in a shuffled set let mut iterator = HashedIter::new_with_seed(NonZeroU32::new(10).unwrap(), 100); for i in iterator { println!("{}", i); }

## Structs

HashedIter | An iterator that allows you to iterate over a sequence of permuted numbers with O(1) space. |

HashedPermutation | The |

## Enums

PermutationError | The different types of errors that can arise from this crate |

## Type Definitions

PermutationResult | A permutation result, which is simply an alias for any type that could return a permutation error. |