At my work I was creating a music player (truly the project is bigger than it but it doesn't come to the case right now) and, given some conditions, it should start playing songs randomly. I've used Random() function to sort any song from the list, but the "random wasn't so random" sometimes, and some songs used to repeat multiple times, although the song list wasn't so small. So I needed to keep a list of all the played songs. However, I couldn't feed up an array forever as this system I'm working on is meant to work 24/7 with no pause and the array could really reach huge values, while just