Does anybody know what mistake can it be?

I also have WA9.
Maybe it's some special case?

At least, AC!

Here's other special cases: the triangle is acute so the minimal distance is the perpendicular and the triangle is obtuse so the minimal distance is the min from C to A and B.

Edited by author 24.03.2005 01:51

AC.
The thing is that the answer to the second question is Max(0, answer).