Are you an optimist or pessimist?

The bottom half of the water suddenly disappear, and we left with vacuum in that space. So because of the atmospheric pressure, the upper half of the water will be pushed down and the glass will be pushed up with the forces of magnitude $F=p_o \pi r^2$ . The acceleration of the water is $a_d=-\frac{F}{\rho \pi r^2 h/2}-g=-\frac{2 p_o}{\rho h}-g=-1010~m/s^2$ and the acceleration of the glass is $a_u=\frac{p_o \pi r^2}{m}-g=3131.6~m/s^2$ . Since $F=dp/dt$ , the momentum of the water and the glass are the same if we neglect the gravitational force, so if we think about the effect of gravity, the momentum of the water is larger than that of the cup, when the water hits the glass, the glass will stop in the air and then it will go down. The highest height in the jumping process can be calculated as:

$H=\frac{a_u}{a_u+a_d}\frac{h}{2}=\frac{\frac{p_o \pi r^2}{m}-g}{\frac{p_o \pi r^2}{m}+\frac{2 p_o}{\rho h}}\frac{h}{2}=7.56(cm)$