arrowsort.go

package main

import (
	"fmt"
	"math/rand"
)

func main() {

	values := randomInts(100)
	fmt.Println(values)
	fmt.Println(ArrowSort(values))
}

const gravity = 9.80665 // m/s

type Arrow struct {
	payload  int
	height   float64
	velocity float64
	landed   bool
}

func (a *Arrow) Fire(velocity float64) {
	a.velocity = velocity
}

func NewArrow(value int) *Arrow {
	return &Arrow{
		payload:  value,
		height:   0.0,
		velocity: 0.0,
	}
}

func (a *Arrow) Tick() bool {
	a.height += a.velocity
	a.velocity -= gravity

	if a.height <= 0 {
		a.landed = true
	}
	return a.landed
}

func ArrowSort(values []int) []int {
	sorted := make([]int, 0, len(values)) // Allocate enough space for the sorted values

	hits := make(chan int)

	arrows := make([]*Arrow, 0, len(values))

	for _, v := range values {
		a := NewArrow(v)
		a.Fire(float64(v))
		arrows = append(arrows, a)
	}

	go func() {
		flying := true
		for flying {
			for _, a := range arrows {

				if !a.landed {

					flying = !a.Tick()

					if !flying {
						hits <- a.payload
					}
				}

			}
		}

		close(hits)
	}()

	for hit := range hits {
		sorted = append(sorted, hit)
	}

	return sorted
}

func randomInts(count int) []int {

	values := make([]int, 0, count)

	for i := 0; i < count; i++ {
		values = append(values, rand.Int()%30)
	}

	return values
}