using binary search r, and check for each segment,find the inner side part of other segment
that distance is smaller than 2*r,get the segment of these points in each line, check if union of them is the hole line segment.

for check two segments' distance we only need to check innerside adjctent two line segments

it can be done by O(n*log(n)) sweepline precalculate..

Why wa26?)
Tests help me to pass test 2 and test 3.
9
1 -1
2 1
1 0
2 2
0 1
-2 2
-1 0
-2 1
-1 -1

1.00

12
2 1
1 1
1 2
-1 2
-1 1
-2 1
-2 -1
-1 -1
-1 -2
1 -2
1 -1
2 -1

1.41

Admins, do you check timus_support@acm.timus.ru from time to time?

My solution to this problem just lacks 1/3 of a solution (actually, the most difficult third of it) - and got AC! I sent the code recognizing that important part of the solution is missing and just wanted to see how far it will reach - but got AC instead. Pity that such a good problem has such a weak testset.

I can mail my tests to you, but it seems nobody checks this mailbox...

Edited by author 16.08.2014 13:34

I've found out that there's a triangle in this test.
My program is likely to find the center of inscribed circle
correctly, so I don't understand where is the mistake.
Can somebody give me more information to pass this test?

Give me some tests, please.

Precision of 1e-8 is ok to get AC (provided that you use only square roots, no trigonomety).

Извиняюсь, что на русском, но английский знаю плохо. В условии задачи на русском языке ошибка - "Тёмыч выгуливает своего любимого козла..." и "...число R — длину веревки, на которую Вася привяжет козла..."