My favourite is this one: https://preshing.com/20121224/how-to-generate-a-sequence-of-unique-random-integers/ https://preshing.com/20121224/how-to-generate-a-se

My favourite is this one: https://preshing.com/20121224/how-to-generate-a-sequence-of-unique-random-integers/ https://preshing.com/20121224/how-to-generate-a-sequence-of-... * Creates a sequence of unique integers * Uses prime numbers that are congruent to P = 3 (mod 4). * A single iteration has noticable patterns but applying it twice already results in randomness that is sufficiently good for many use cases. * It is "embarrassingly parallel", a simple mapping of randomValue = randomize(i). You can calculate unique and deterministic random numbers from input i in parallel threads with no sync between threads. * Since it is a unique mapping of i to r, you can use it to shuffle data sets virtually instantly. Take the index of a value in the original array, and use it to compute the target index in the shuffled array. * I've used it to shuffle up to 800 million items per second on a GPU, including the time it took to transfer the data from RAM to GPU. So without the IO, you could probably shuffle billions of values per second, probably mostly bound by GPU bandwidth. E.g., 700GB/s and each item is 70 bytes -> could perhabs shuffle 10 billion items per second.