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Designing an elevator car call control system
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| package main | |
| import ( | |
| "fmt" | |
| "sort" | |
| ) | |
| /* | |
| Designing an elevator car call control system | |
| Specifically, the algo for finding what is the next floor to go to. | |
| - if there are no calls, go to the ground floor | |
| - if there are calls, go to the closest call in the same direction already in progress | |
| - else go to the closest call in the opposite direction and change direction | |
| */ | |
| // when direction change, we reverse the order of the calls | |
| type CallList struct { | |
| UpList []int | |
| DownList []int | |
| Direction int | |
| CurrentFloor int | |
| MaxFloor int | |
| } | |
| func NewCallList() *CallList { | |
| return &CallList{ | |
| Direction: 0, | |
| CurrentFloor: 2, | |
| MaxFloor: 10, | |
| UpList: make([]int, 0), | |
| DownList: make([]int, 0), | |
| } | |
| } | |
| func isDupe(x int, list []int) bool { | |
| for _, v := range list { | |
| if v == x { | |
| return true | |
| } | |
| } | |
| return false | |
| } | |
| func (c *CallList) AddStop(floor int) { | |
| if floor > c.CurrentFloor { | |
| if c.Direction == 0 { | |
| c.Direction = 1 | |
| } | |
| if !isDupe(floor, c.UpList) { | |
| fmt.Printf("adding floor %d\n", floor) | |
| c.UpList = append(c.UpList, floor) | |
| sort.Ints(c.UpList) | |
| } | |
| } else { | |
| if c.Direction == 0 { | |
| c.Direction = -1 | |
| } | |
| if !isDupe(floor, c.DownList) { | |
| fmt.Printf("adding floor %d\n", floor) | |
| c.DownList = append(c.DownList, floor) | |
| // reverse order sort | |
| sort.Sort(sort.Reverse(sort.IntSlice(c.DownList))) | |
| } | |
| } | |
| } | |
| func (c *CallList) GetStops() []int { | |
| if c.Direction == 1 { | |
| return append(c.UpList, c.DownList...) | |
| } else { | |
| return append(c.DownList, c.UpList...) | |
| } | |
| } | |
| func (c *CallList) move() { | |
| if len(c.UpList) == 0 && len(c.DownList) == 0 { | |
| c.Direction = 0 | |
| fmt.Println("no more stops") | |
| return | |
| } else if len(c.UpList) == 0 && c.Direction == 1 { | |
| c.Direction = -1 | |
| } else if len(c.DownList) == 0 && c.Direction == -1 { | |
| c.Direction = 1 | |
| } | |
| // move in the same direction as we're already going until we've emptied that list | |
| if c.Direction == 1 { | |
| if len(c.UpList) > 0 { | |
| c.CurrentFloor = c.UpList[0] | |
| c.UpList = c.UpList[1:] | |
| } else { | |
| c.CurrentFloor = c.DownList[0] | |
| c.DownList = c.DownList[1:] | |
| c.Direction = -1 | |
| } | |
| } else { | |
| if len(c.DownList) > 0 { | |
| c.CurrentFloor = c.DownList[0] | |
| c.DownList = c.DownList[1:] | |
| } else { | |
| c.CurrentFloor = c.UpList[0] | |
| c.UpList = c.UpList[1:] | |
| c.Direction = 1 | |
| } | |
| } | |
| fmt.Println("moving to floor", c.CurrentFloor) | |
| } | |
| func main() { | |
| c := NewCallList() | |
| c.AddStop(3) | |
| c.AddStop(5) | |
| fmt.Println(c.GetStops()) | |
| c.move() | |
| c.AddStop(2) | |
| c.AddStop(4) | |
| fmt.Println(c.GetStops()) | |
| c.move() | |
| c.AddStop(5) | |
| c.AddStop(1) | |
| fmt.Println(c.GetStops()) | |
| c.move() | |
| c.move() | |
| c.move() | |
| c.move() | |
| } |
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