Looking for a YA book title...?

I recently remembered a YA book about a girl who is taken from her normal life and thrust into a cl-based world where she must work in the bottom-most cl (I think they're referred to as 'the Rations') and be constantly pitted against the upper cl in games and projects. She makes friends with very young girl who ends up getting shot and killed. Sadly, this is all I can remember, since I was reminded through a dream. Honestly, I'm only about 75% sure this was a real book, so if anyone can help me out, I'd appreciate it!