N cars are going to the same destination along a one lane road. The destination is target miles away.
Each car i has a constant speed speed[i] (in miles per hour), and initial position position[i] miles towards the target along the road.
A car can never pass another car ahead of it, but it can catch up to it, and drive bumper to bumper at the same speed.
The distance between these two cars is ignored - they are assumed to have the same position.
A car fleet is some non-empty set of cars driving at the same position and same speed. Note that a single car is also a car fleet.
Input: target = 12, position = [10,8,0,5,3], speed = [2,4,1,1,3]
The cars starting at 10 and 8 become a fleet, meeting each other at 12.
The car starting at 0 doesn’t catch up to any other car, so it is a fleet by itself.
The cars starting at 5 and 3 become a fleet, meeting each other at 6.
Note that no other cars meet these fleets before the destination, so the answer is 3.
0 <= N <= 10 ^ 4
0 < target <= 10 ^ 6
0 < speed[i] <= 10 ^ 6
0 <= position[i] < target
All initial positions are different.
- 显然我们先根据车的位置进行排序，从前面的车开始分析，如有A,B,C,D,E 5辆车，p[a] > p[b] > p[c] >…
- 假设B,C都能追上A，D追不上，那么显然D也不可能追上C，我们就把D当做此时最前面的车开始分析就行了，所以是O(n),one pass，不会重复计算，但是排序本身是O(nlogn)