func (t *Trip) Score(gifts *map[int]gift.Gift) float64 {
// NB - compute cost in reverse for efficiency
lastPos := location.NorthPole
tripWeight := sleighWeight
tripWRW := 0.0
giftWeight := 0.0
if len(t.Gifts) == 0 {
fmt.Println("Warning, empty trip")
os.Exit(1)
}
gids := t.Gifts
for i := len(gids) - 1; i >= 0; i-- {
g := (*gifts)[gids[i]]
tripWRW += location.Dist(g.Location, lastPos) * tripWeight
lastPos = g.Location
tripWeight += g.Weight
giftWeight += g.Weight
}
if (t.Id >= 0) && (giftWeight > WeightLimit) {
fmt.Println("Warning: Trip ", t.Id, " over weight limit")
}
tripWRW += location.Dist(location.NorthPole,
(*gifts)[gids[0]].Location) * tripWeight
return tripWRW
}
func (t *Trip) OptimizeOrder(gifts *map[int]gift.Gift) {
// Find the gift with the highest cost
heaviestGid := -1
maxCost := 0.0
gids := t.Gifts
tripWeight := 0.0
for _, gid := range gids {
g := (*gifts)[gid]
tripWeight += g.Weight
cost := location.Dist(location.NorthPole, g.Location) * g.Weight
if cost > maxCost {
heaviestGid = gid
maxCost = cost
}
}
// Start new list and identify remaining gifts
newGids := []int{heaviestGid}
remGifts := make(map[int]bool)
for _, gid := range gids {
if gid != heaviestGid {
remGifts[gid] = true
}
}
// Loop until no remaining gifts
lastGid := heaviestGid
tripWeight -= (*gifts)[lastGid].Weight
for len(remGifts) > 0 {
bestGid := -1
bestCost := math.Inf(0)
lastG := (*gifts)[lastGid]
for gid, _ := range remGifts {
g := (*gifts)[gid]
cost := location.Dist(lastG.Location, g.Location) * tripWeight
if cost < bestCost {
bestGid = gid
bestCost = cost
}
}
// Add to new list and remove from map
newGids = append(newGids, bestGid)
tripWeight -= (*gifts)[bestGid].Weight
delete(remGifts, bestGid)
}
t.Gifts = newGids
}