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queue.go
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queue.go
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package priority
//generic implementation of priority queue example found at https://pkg.go.dev/container/heap#example-package-PriorityQueue
type Item[T any] struct {
Value T
priority int
index int
}
type Queue[T any] []*Item[T]
func (q Queue[T]) Len() int {
return len(q)
}
func (q Queue[T]) Less(i, j int) bool {
return q[i].priority < q[j].priority
}
func (q Queue[T]) Swap(i, j int) {
q[i], q[j] = q[j], q[i]
q[i].index = i
q[j].index = j
}
func (q *Queue[T]) Push(item *Item[T]) {
n := len(*q)
item.index = n
*q = append(*q, item)
}
func (q *Queue[T]) Pop() *Item[T] {
old := *q
n := len(old)
item := old[n-1]
old[n-1] = nil
item.index = -1
*q = old[0 : n-1]
return item
}
func (q *Queue[T]) Update(item *Item[T], value T, priority int) {
item.Value = value
item.priority = priority
Fix[*Item[T]](q, item.index)
}