17 Dec 2011
I do believe that given a problem,
You either solve it or you don't
If you don't, you need to seek for a solution elsewhere.
It's probably a little exaggerated. But if you see a problem and you cannot solve it within an hour, you should give it up and find a solution elsewhere instead.
A solution emerges from your mind; It's not something you can deduce from.
As Polya used to say,
All mathematics theories are first guessed, then proved
Theories emerge in mathematicians' minds, then they try to prove it. If they succeed, then they are famous. If they don't, then they wait until another hits their minds, and they try again.
So, if you cannot solve any problem within an hour or so, find the solution on the internet or talk to other people about it.