86 lines
1.4 KiB
Go
86 lines
1.4 KiB
Go
package car_fleet
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import (
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"fmt"
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"math"
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"slices"
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)
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type Car struct {
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position int
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speed int
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}
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func (c Car) CollidesInto(o Car) float64 {
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if c.speed == o.speed {
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return math.Inf(1)
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}
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return float64(c.position-o.position) / float64(o.speed-c.speed)
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}
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func (c Car) At(time int) int {
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return c.position + c.speed*time
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}
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type CarSpace struct {
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car Car
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from float64
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to float64
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}
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func (s CarSpace) Contains(point float64) bool {
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return point >= float64(s.from) && point <= float64(s.to)
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}
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func sortByInversePosition(a Car, b Car) int {
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return b.position - a.position
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}
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func CarFleet(target int, position []int, speed []int) int {
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cars := []Car{}
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ends := map[int]bool{}
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for i := range position {
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cars = append(cars, Car{
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position: position[i],
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speed: speed[i],
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})
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}
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slices.SortFunc(cars, sortByInversePosition)
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stack := []CarSpace{}
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for _, car := range cars {
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for {
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fmt.Println(car, stack)
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if len(stack) == 0 {
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stack = append(stack, CarSpace{
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car: car,
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from: 0,
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to: float64(target),
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})
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break
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}
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top := stack[len(stack)-1]
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time := car.CollidesInto(top.car)
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if top.Contains(time) {
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stack[len(stack)-1].from = time
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stack = append(stack, CarSpace{
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car: car,
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from: 0,
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to: time,
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})
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break
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}
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stack = stack[:len(stack)-1]
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}
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ending_at := stack[0].car.At(target)
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ends[ending_at] = true
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}
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return len(ends)
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}
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