Stupendous Permutations

Sperm is a random permutations generator based on the ideas of group theory that allows you to generate very large permutations without extra memory consumption.

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Installation

Add this line to your application's Gemfile: ruby gem 'sperm'

And then execute: bash $ bundle

Or install it yourself as: bash $ gem install sperm

Usage

Sperm.rand(5).each { |element| puts element }

This is a shorthand for: ruby Sperm::RandomPermutations.new(5).rand.each { |element| puts element }

You can also use your own source of randomness: ruby Sperm::RandomPermutations.new(5, Random.new(42)) Sperm::RandomPermutations.new(10**8, SecureRandom)

How it works

Computational complexity

Operation Time complexity Space complexity
Initialization O(n/ϕ(n) · log(n)) O(1)
Generation of next element O(1) O(1)

Copyright

Copyright © 2014 Arthur Khashaev. See LICENSE.txt for details.