ZOJ Problem Set - 2086
Cut a round pipe into halves, take away one, and put the other on the plumb
plane. Two ends of the half-round pipe are horizontal. Then put 2*n same balls
whose radius are equal to the pipe's into the pipe. Be sure the left one and
the right one are just tangent with the pipe's ends.
Input consists of several test cases. Each case will contain 2 positive integer
n and k. (2 <= n <= 100, 1 <= k < 2 * n)
Output the pressure between the the kth and the (k+1)th ball. Check it in the sample. Accurate to 2 decimal places.
Author: YU, Xing
Source: ZOJ Monthly, February 2004