[原创]UVAlive 7308 Tom and Jerry 【几何数学】

2016-06-26 19:17:17 Tabris_ 阅读数：497

https://blog.csdn.net/qq_33184171/article/details/51763961

Tom and Jerry are very fond of cat and mice games, which might be rather obvious to you. Today they
are playing a very complicated game. The goals are simple as usual though, Jerry would be running
and Tom would have to catch Jerry.
However, today Jerry is running on a perfect circular
path with radius R meters, at a constant speed of
V m/s. Initially Tom is sitting at the very center of
the circle. He wants to catch Jerry as soon as possible,
but we all know, Tom is not very intelligent. Instead
of calculating an optimal direction to catch Jerry, he is
just running towards Jerry.
As Jerry is also moving, the path Tom has taken
start to look like a curve (see picture above). At any
given moment, Tom’s position is between Jerry’s current
position and the center of the circle. Tom is also
moving at a constant speed of V m/s, same speed as
Jerry. Find the time (in seconds) Tom would need to
catch Jerry.
Input
Input file has T (T ≤ 10000) test cases, each case consists of two integer R and V . Here, 0 < R, V ≤
10000.
Output
For each test case, print the case number and the time Tom will need to catch Jerry. Floating point
rounding error lower than 10−5 will be ignored by the judge.
Sample Input
4
45 100
5 1547
1000 10000
5668 5467
Sample Output
Case 1: 0.70685835
Case 2: 0.00507691
Case 3: 0.15707963
Case 4: 1.62854830

t=2 * PI * r/4 / v;