What is test 4, there is a question about it but I don't understand the answer.
All the eigenvalues are positive integers not exceeding 10^9. Does it mean they are non-zeros? My solution assumes there are not zeros, maybe that's the cause of WA.
And why do I get compilation error using Visual C 2010? It's ignoring semicolons.

Sorry for this topic, I just initialized array to -1 instead of zero, and tested against it.