114 lines
2.9 KiB
Swift
114 lines
2.9 KiB
Swift
/**
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* File: array_queue.swift
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* Created Time: 2023-01-11
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* Author: nuomi1 (nuomi1@qq.com)
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*/
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/* Queue class based on circular array */
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class ArrayQueue {
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private var nums: [Int] // Array for storing queue elements
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private var front: Int // Front pointer, pointing to the front element
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private var _size: Int // Queue length
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init(capacity: Int) {
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// Initialize an array
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nums = Array(repeating: 0, count: capacity)
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front = 0
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_size = 0
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}
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/* Get the capacity of the queue */
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func capacity() -> Int {
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nums.count
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}
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/* Get the length of the queue */
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func size() -> Int {
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_size
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}
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/* Determine if the queue is empty */
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func isEmpty() -> Bool {
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size() == 0
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}
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/* Enqueue */
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func push(num: Int) {
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if size() == capacity() {
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print("Queue is full")
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return
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}
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// Calculate rear pointer, pointing to rear index + 1
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// Use modulo operation to wrap the rear pointer from the end of the array back to the start
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let rear = (front + size()) % capacity()
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// Add num to the rear
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nums[rear] = num
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_size += 1
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}
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/* Dequeue */
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@discardableResult
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func pop() -> Int {
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let num = peek()
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// Move front pointer one position backward, returning to the head of the array if it exceeds the tail
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front = (front + 1) % capacity()
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_size -= 1
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return num
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}
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/* Access front element */
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func peek() -> Int {
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if isEmpty() {
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fatalError("Queue is empty")
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}
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return nums[front]
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}
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/* Return array */
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func toArray() -> [Int] {
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// Only convert elements within valid length range
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(front ..< front + size()).map { nums[$0 % capacity()] }
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}
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}
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@main
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enum _ArrayQueue {
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/* Driver Code */
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static func main() {
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/* Initialize queue */
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let capacity = 10
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let queue = ArrayQueue(capacity: capacity)
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/* Element enqueue */
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queue.push(num: 1)
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queue.push(num: 3)
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queue.push(num: 2)
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queue.push(num: 5)
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queue.push(num: 4)
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print("Queue queue = \(queue.toArray())")
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/* Access front element */
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let peek = queue.peek()
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print("Front element peek = \(peek)")
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/* Element dequeue */
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let pop = queue.pop()
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print("Dequeued element pop = \(pop), queue after dequeue = \(queue.toArray())")
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/* Get the length of the queue */
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let size = queue.size()
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print("Queue length size = \(size)")
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/* Determine if the queue is empty */
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let isEmpty = queue.isEmpty()
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print("Is the queue empty = \(isEmpty)")
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/* Test circular array */
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for i in 0 ..< 10 {
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queue.push(num: i)
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queue.pop()
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print("After the \(i)th round of enqueue + dequeue, queue = \(queue.toArray())")
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}
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}
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}
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