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export class Queue<T = any> {
private existsMap: Map<T, boolean> = new Map()
private firstItem: QueueItem<T> | null = null
private lastItem: QueueItem<T> | null = null
add(value: T) {
if (!this.existsMap.has(value)) {
this.existsMap.set(value, true)
const item = {
current: value,
next: null,
}
if (!this.firstItem) {
this.firstItem = item
}
if (this.lastItem) {
this.lastItem.next = item
}
this.lastItem = item
}
}
shift(): T | null {
if (this.firstItem) {
const item = this.firstItem
this.firstItem = item.next
if (!this.firstItem) {
this.lastItem = null
}
this.existsMap.delete(item.current)
return item.current
}
return null
}
isEmpty() {
return !this.firstItem
}
has(value: T) {
return this.existsMap.has(value)
}
}
interface QueueItem<T> {
current: T
next: QueueItem<T> | null
}
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