There are n cars on a one-lane road driving toward a target mile. position[i] is the starting mile and speed[i] the speed (miles per hour) of car i. A car can never pass another; if it catches up to a slower car ahead it slows to that car's speed and from then on they travel together as one fleet, and a car that catches up exactly at the target also joins that fleet.
Return the number of fleets that arrive at the target.
carFleet(12, [10, 8, 0, 5, 3], [2, 4, 1, 1, 3]) is 3- All starting positions are distinct and below
target; the input is not sorted