114 lines
2.8 KiB
Swift
114 lines
2.8 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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/* 基於環形陣列實現的佇列 */
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class ArrayQueue {
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private var nums: [Int] // 用於儲存佇列元素的陣列
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private var front: Int // 佇列首指標，指向佇列首元素
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private var _size: Int // 佇列長度
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init(capacity: Int) {
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// 初始化陣列
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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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/* 獲取佇列的容量 */
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func capacity() -> Int {
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nums.count
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}
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/* 獲取佇列的長度 */
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func size() -> Int {
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_size
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}
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/* 判斷佇列是否為空 */
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func isEmpty() -> Bool {
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size() == 0
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}
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/* 入列 */
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func push(num: Int) {
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if size() == capacity() {
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print("佇列已滿")
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return
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}
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// 計算佇列尾指標，指向佇列尾索引 + 1
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// 透過取餘操作實現 rear 越過陣列尾部後回到頭部
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let rear = (front + size()) % capacity()
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// 將 num 新增至佇列尾
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nums[rear] = num
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_size += 1
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}
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/* 出列 */
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@discardableResult
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func pop() -> Int {
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let num = peek()
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// 佇列首指標向後移動一位，若越過尾部，則返回到陣列頭部
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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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/* 訪問佇列首元素 */
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func peek() -> Int {
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if isEmpty() {
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fatalError("佇列為空")
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}
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return nums[front]
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}
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/* 返回陣列 */
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func toArray() -> [Int] {
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// 僅轉換有效長度範圍內的串列元素
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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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/* 初始化佇列 */
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let capacity = 10
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let queue = ArrayQueue(capacity: capacity)
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/* 元素入列 */
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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("佇列 queue = \(queue.toArray())")
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/* 訪問佇列首元素 */
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let peek = queue.peek()
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print("佇列首元素 peek = \(peek)")
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/* 元素出列 */
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let pop = queue.pop()
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print("出列元素 pop = \(pop)，出列後 queue = \(queue.toArray())")
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/* 獲取佇列的長度 */
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let size = queue.size()
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print("佇列長度 size = \(size)")
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/* 判斷佇列是否為空 */
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let isEmpty = queue.isEmpty()
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print("佇列是否為空 = \(isEmpty)")
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/* 測試環形陣列 */
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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("第 \(i) 輪入列 + 出列後 queue = \(queue.toArray())")
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}
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}
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}
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