Reddit reviews Shadows: A Novel

Is it Shadows by John Saul?

I searched yahoo answers for the query "book boy goes to a school for students brains kill".

There was someone else trying to figure out a book similar, and here's what they remembered:
>...A really smart boy is sent to a special school. All the students there are prodigies. Turns out the dean of the school is using the children to harvest their brains to use as part of a super computer...

Here is the book on google book search at the exact page (81) where Josh tells Amy that he thinks he flunked the test, and she responds that she didn't even finish half of it.

Is it Shadows by John Saul? The description sounds right.

The Shadows by John Saul ?
https://www.google.com/url?sa=t&source=web&rct=j&ei=VXU3VIvhPOXDigKmrIG4Cg&url=http://www.amazon.com/gp/aw/d/0553560271%3Fpc_redir%3D1411904437%26robot_redir%3D1&ved=0CGoQFjAK&usg=AFQjCNHqRcR2-FuQLCspW55c70I44o47WA&sig2=OYKfTbiNg9pI5qXBtS176Q

Read 'Shadows' by John Saul

Look at the book on Amazon. It's got an option to see some of the pages. Link here