I'm hoping to identify a YA novel I read around when Hunger Games started to get popular (2012ish? I don't know if the novel was released then though). It's got quite a Hunger Games vibe to it.
It was set in a post disaster world - I think it was set in a future England but there had been a terrible war. The nation had been gloriously rescued by the King though, and it was rebuilding. It was a very structured life though, people lived in the villages/towns they were told to live in.
It started with the protagonist (female, 17ish? I don't remember her name) taking a special exam. The exam sorted you into one of several classes. Every year a small number of people from each class were selected to go and serve the king. The protagonist is chosen, and she's happy as it's considered to be a great honour to be chosen.
On the train down to where the king lives she befriends one of the other people selected. He's in the lowest class though so some of the other Chosen are snobby to him.
When they arrive they go to a fantastic dinner. However her new friend makes an etiquette mistake, and the king runs him through with a sword. The king then forces one of the prettiest girls to go to bed with him.
The king is shown to be a cruel man who likely overthrew the real hero of the war. The rest of the book covers how the group of Chosen try to survive; however they're regularly killed and tortured.
Eventually the protagonist manages to lead a small group out, and they manage to broadcast to the nation what it's actually like to be one of the Chosen.