Solving T72 Height Simulation

[xh092113]

• Instead of maintaining heights of the missiles, we can maintain the distance (from being launched) of them. (In code, by adding the CalculateDistance() function, and the startingpoint_ parameter)
• We extend the IsBlockedByObstacles() function to MissileBlockedByObstacles() function, taking the distance into consideration.
• When dis > 12.0, we consider the missile to have returned to the ground.
• When 4.0 <= dis <= 8.0, we say the missile cannot be blocked by any obstacle.
• In other cases, we still call the IsBlockedByObstacles() function.