I do not understand why, but my program gives different result, than sample. in this picture, i draw a figure with yellow, i think area of this figure is an answer, i am right ? download this picture: http://slil.ru/28091271Question is simple. H is not diven then we have plane problem. Two adjacent, rejion after antey+ antey itself. You filled with yellow only the area behind the new building. But the big inner circle must be included in "nonseen" region as well. I think, that this problem can be solved only via integrals. Analytic geometry doesn't work. I am right? No!i tried to use integral during contest: WA8 rounding error. At the next day I found simple analytic solution. Are you sure, that it is simple solution? =) A think, that main problem is that we can't make any Circle Sector, except sector from the center of town, so we can't find exact area behind New Antey Building. Areas of figures with rounded border are hardly calculated. The figure can be decomposed into triangles and circle segments. All lengths and , therefore areas are easy calculated, typical school problem. Edited by author 18.10.2009 17:15 Solution on Java exists! No problems with accuracy of calculating. the link for the diagram has expired can anyone draw a figure and upload again, the area to find out is unclear to refer to from the question. The new tower blocks its own area plus all the town behind it. This sum needs to be divided by (pi * R**2) and multiplied by 100. My program get AC, but lets consider test case from another forum thread: 1000 1 498 0 500 my ans is 46.5715285623 but another person answer is 46.5 Please, check it! 46.5715285623 is a correct answer. Hi all! I have problems with test 7 and I wonder whether wrong idea causes it or not... please, tell me, what the answer for 1000 1 498 0 500 Is it 46.541438420 ? thx. precision!!! thx ). btw, how much digits are right ? 46.5  it is right, but than..... ok. thank you again. I print all digits of answer =) oh, gosh! In the long run I found that I had an idea problem, not precision. Thanks to all, AC now. 
