I am not getting my mistake in this question. I am trying to find out the circle whose y co-ordinate is maximum and also new circle is touching this circle and then calculating y co-ordinate of new circle. Here is link to my code. http://codeforces.com/contest/908/submission/33866310
You miss a situation... It is possible that y[A]<y[B], but y[A] + delta y_a > y[B] + delta y_b
The circle that hits is not the circle with the highest y-coordinate. Rather, it is the circle which causes the disk thrown to have the highest y-value.