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DSA
HardArray

Car Fleet II

arraymathstack

Problem Statement

There are n cars traveling at different speeds in the same direction along a one-lane road. You are given an array cars of length n , where cars[i] = [position _i , speed _i ] represents:

position _i is the distance between the i ^th car and the beginning of the road in meters. It is guaranteed that position _i < position _i+1 .

speed _i is the initial speed of the i ^th car in meters per second.

For simplicity, cars can be considered as points moving along the number line. Two cars collide when they occupy the same position. Once a car collides with another car, they unite and form a single car fleet. The cars in the formed fleet will have the same position and the same speed, which is the initial speed of the slowest car in the fleet.

Return an array answer , where answer[i] is the time, in seconds, at which the i ^th car collides with the next car, or -1 if the car does not collide with the next car. Answers within 10 ^-5 of the actual answers are accepted.

Examples

Example 1
Input: cars = [[1,2],[2,1],[4,3],[7,2]]
Output: [1.00000,-1.00000,3.00000,-1.00000]
After exactly one second, the first car will collide with the second car, and form a car fleet with speed 1 m/s. After exactly 3 seconds, the third car will collide with the fourth car, and form a car fleet with speed 2 m/s.
Example 2
Input: cars = [[3,4],[5,4],[6,3],[9,1]]
Output: [2.00000,1.00000,1.50000,-1.00000]

Constraints

1 <= cars.length <= 10 ^5
1 <= position _i , speed _i <= 10 ^6
position _i < position _i+1
😤
Hard
Difficulty
Topic Info
ModuleDSA
CategoryArray
Sub-topicMath
Tags
arraymathstackheap (priority queue)monotonic stack
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