149 lines
4.0 KiB
Swift
149 lines
4.0 KiB
Swift
/**
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* File: array_deque.swift
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* Created Time: 2023-02-22
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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雙向佇列 */
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class ArrayDeque {
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private var nums: [Int] // 用於儲存雙向佇列元素的陣列
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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 // 雙向佇列長度
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/* 建構子 */
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init(capacity: Int) {
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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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/* 獲取雙向佇列的容量 */
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func capacity() -> Int {
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nums.count
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}
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/* 獲取雙向佇列的長度 */
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func size() -> Int {
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_size
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}
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/* 判斷雙向佇列是否為空 */
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func isEmpty() -> Bool {
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size() == 0
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}
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/* 計算環形陣列索引 */
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private func index(i: Int) -> Int {
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// 透過取餘操作實現陣列首尾相連
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// 當 i 越過陣列尾部後，回到頭部
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// 當 i 越過陣列頭部後，回到尾部
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(i + capacity()) % capacity()
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}
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/* 佇列首入列 */
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func pushFirst(num: Int) {
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if size() == capacity() {
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print("雙向佇列已滿")
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return
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}
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// 佇列首指標向左移動一位
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// 透過取餘操作實現 front 越過陣列頭部後回到尾部
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front = index(i: front - 1)
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// 將 num 新增至佇列首
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nums[front] = num
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_size += 1
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}
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/* 佇列尾入列 */
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func pushLast(num: Int) {
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if size() == capacity() {
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print("雙向佇列已滿")
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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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let rear = index(i: front + size())
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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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/* 佇列首出列 */
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func popFirst() -> Int {
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let num = peekFirst()
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// 佇列首指標向後移動一位
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front = index(i: front + 1)
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_size -= 1
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return num
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}
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/* 佇列尾出列 */
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func popLast() -> Int {
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let num = peekLast()
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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 peekFirst() -> Int {
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if isEmpty() {
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fatalError("雙向佇列為空")
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}
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return nums[front]
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}
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/* 訪問佇列尾元素 */
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func peekLast() -> Int {
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if isEmpty() {
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fatalError("雙向佇列為空")
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}
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// 計算尾元素索引
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let last = index(i: front + size() - 1)
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return nums[last]
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}
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/* 返回陣列用於列印 */
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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[index(i: $0)] }
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}
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}
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@main
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enum _ArrayDeque {
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/* Driver Code */
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static func main() {
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/* 初始化雙向佇列 */
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let deque = ArrayDeque(capacity: 10)
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deque.pushLast(num: 3)
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deque.pushLast(num: 2)
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deque.pushLast(num: 5)
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print("雙向佇列 deque = \(deque.toArray())")
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/* 訪問元素 */
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let peekFirst = deque.peekFirst()
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print("佇列首元素 peekFirst = \(peekFirst)")
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let peekLast = deque.peekLast()
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print("佇列尾元素 peekLast = \(peekLast)")
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/* 元素入列 */
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deque.pushLast(num: 4)
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print("元素 4 佇列尾入列後 deque = \(deque.toArray())")
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deque.pushFirst(num: 1)
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print("元素 1 佇列首入列後 deque = \(deque.toArray())")
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/* 元素出列 */
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let popLast = deque.popLast()
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print("佇列尾出列元素 = \(popLast)，佇列尾出列後 deque = \(deque.toArray())")
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let popFirst = deque.popFirst()
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print("佇列首出列元素 = \(popFirst)，佇列首出列後 deque = \(deque.toArray())")
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/* 獲取雙向佇列的長度 */
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let size = deque.size()
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print("雙向佇列長度 size = \(size)")
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/* 判斷雙向佇列是否為空 */
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let isEmpty = deque.isEmpty()
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print("雙向佇列是否為空 = \(isEmpty)")
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}
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}
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