There are ways to check for pseudo-randomness.

Sorry but this is not clever at all. Unless you're trying to find the most expensive algorithm to get the result...

Nope, that's not an issue.

this must cost huge mount of time ..

OMG, this is brutal...

The brute force is real

Thanks!

The tip in your first paragraph helped me to finally meet the speed requirement. Thanks!

Likewise - a test for 1==1 (with no other tests) just times out...
[Update 19/07/16] - now seems to be fixed

I guess there's a trade-off between using range with str() or writing the numbers out all those times. Maybe put the numbers into a variable?

I don't think there are necessarily edge cases if you implement the right solution

Change expect to assert