Merge pull request #240 from nuomi1/feature/queue-Swift

feat: add Swift codes for queue article

codes/swift/Package.swift

@@ -16,6 +16,9 @@ let package = Package(
         .executable(name: "stack", targets: ["stack"]),
         .executable(name: "linkedlist_stack", targets: ["linkedlist_stack"]),
         .executable(name: "array_stack", targets: ["array_stack"]),
+        .executable(name: "queue", targets: ["queue"]),
+        .executable(name: "linkedlist_queue", targets: ["linkedlist_queue"]),
+        .executable(name: "array_queue", targets: ["array_queue"]),
     ],
     targets: [
         .target(name: "utils", path: "utils"),
@@ -30,5 +33,8 @@ let package = Package(
         .executableTarget(name: "stack", path: "chapter_stack_and_queue", sources: ["stack.swift"]),
         .executableTarget(name: "linkedlist_stack", dependencies: ["utils"], path: "chapter_stack_and_queue", sources: ["linkedlist_stack.swift"]),
         .executableTarget(name: "array_stack", path: "chapter_stack_and_queue", sources: ["array_stack.swift"]),
+        .executableTarget(name: "queue", path: "chapter_stack_and_queue", sources: ["queue.swift"]),
+        .executableTarget(name: "linkedlist_queue", dependencies: ["utils"], path: "chapter_stack_and_queue", sources: ["linkedlist_queue.swift"]),
+        .executableTarget(name: "array_queue", path: "chapter_stack_and_queue", sources: ["array_queue.swift"]),
     ]
 )

codes/swift/chapter_stack_and_queue/array_queue.swift

@@ -0,0 +1,116 @@
+/**
+ * File: array_queue.swift
+ * Created Time: 2023-01-11
+ * Author: nuomi1 (nuomi1@qq.com)
+ */
+
+/* 基于环形数组实现的队列 */
+class ArrayQueue {
+    private var nums: [Int] // 用于存储队列元素的数组
+    private var front = 0 // 头指针，指向队首
+    private var rear = 0 // 尾指针，指向队尾 + 1
+
+    init(capacity: Int) {
+        // 初始化数组
+        nums = Array(repeating: 0, count: capacity)
+    }
+
+    /* 获取队列的容量 */
+    func capacity() -> Int {
+        nums.count
+    }
+
+    /* 获取队列的长度 */
+    func size() -> Int {
+        let capacity = capacity()
+        // 由于将数组看作为环形，可能 rear < front ，因此需要取余数
+        return (capacity + rear - front) % capacity
+    }
+
+    /* 判断队列是否为空 */
+    func isEmpty() -> Bool {
+        rear - front == 0
+    }
+
+    /* 入队 */
+    func offer(num: Int) {
+        if size() == capacity() {
+            print("队列已满")
+            return
+        }
+        // 尾结点后添加 num
+        nums[rear] = num
+        // 尾指针向后移动一位，越过尾部后返回到数组头部
+        rear = (rear + 1) % capacity()
+    }
+
+    /* 出队 */
+    @discardableResult
+    func poll() -> Int {
+        let num = peek()
+        // 队头指针向后移动一位，若越过尾部则返回到数组头部
+        front = (front + 1) % capacity()
+        return num
+    }
+
+    /* 访问队首元素 */
+    func peek() -> Int {
+        if isEmpty() {
+            fatalError("队列为空")
+        }
+        return nums[front]
+    }
+
+    /* 返回数组 */
+    func toArray() -> [Int] {
+        let size = size()
+        let capacity = capacity()
+        // 仅转换有效长度范围内的列表元素
+        var res = Array(repeating: 0, count: size)
+        for (i, j) in sequence(first: (0, front), next: { $0 < size - 1 ? ($0 + 1, $1 + 1) : nil }) {
+            res[i] = nums[j % capacity]
+        }
+        return res
+    }
+}
+
+@main
+enum _ArrayQueue {
+    /* Driver Code */
+    static func main() {
+        /* 初始化队列 */
+        let capacity = 10
+        let queue = ArrayQueue(capacity: capacity)
+
+        /* 元素入队 */
+        queue.offer(num: 1)
+        queue.offer(num: 3)
+        queue.offer(num: 2)
+        queue.offer(num: 5)
+        queue.offer(num: 4)
+        print("队列 queue = \(queue.toArray())")
+
+        /* 访问队首元素 */
+        let peek = queue.peek()
+        print("队首元素 peek = \(peek)")
+
+        /* 元素出队 */
+        let poll = queue.poll()
+        print("出队元素 poll = \(poll)，出队后 queue = \(queue.toArray())")
+
+        /* 获取队列的长度 */
+        let size = queue.size()
+        print("队列长度 size = \(size)")
+
+        /* 判断队列是否为空 */
+        let isEmpty = queue.isEmpty()
+        print("队列是否为空 = \(isEmpty)")
+
+        /* 测试环形数组 */
+        for i in 0 ..< 10 {
+            queue.offer(num: i)
+            queue.poll()
+            print("第 \(i) 轮入队 + 出队后 queue = \(queue.toArray())")
+        }
+    }
+}

codes/swift/chapter_stack_and_queue/array_stack.swift

@@ -29,8 +29,9 @@ class ArrayStack {
     }
 
     /* 出栈 */
+    @discardableResult
     func pop() -> Int {
-        if stack.isEmpty {
+        if isEmpty() {
             fatalError("栈为空")
         }
         return stack.removeLast()
@@ -38,7 +39,7 @@ class ArrayStack {
 
     /* 访问栈顶元素 */
     func peek() -> Int {
-        if stack.isEmpty {
+        if isEmpty() {
             fatalError("栈为空")
         }
         return stack.last!

codes/swift/chapter_stack_and_queue/linkedlist_queue.swift

@@ -0,0 +1,105 @@
+/**
+ * File: linkedlist_queue.swift
+ * Created Time: 2023-01-11
+ * Author: nuomi1 (nuomi1@qq.com)
+ */
+
+import utils
+
+/* 基于链表实现的队列 */
+class LinkedListQueue {
+    private var front: ListNode? // 头结点
+    private var rear: ListNode? // 尾结点
+    private var _size = 0
+
+    init() {}
+
+    /* 获取队列的长度 */
+    func size() -> Int {
+        _size
+    }
+
+    /* 判断队列是否为空 */
+    func isEmpty() -> Bool {
+        size() == 0
+    }
+
+    /* 入队 */
+    func offer(num: Int) {
+        // 尾结点后添加 num
+        let node = ListNode(x: num)
+        // 如果队列为空，则令头、尾结点都指向该结点
+        if front == nil {
+            front = node
+            rear = node
+        }
+        // 如果队列不为空，则将该结点添加到尾结点后
+        else {
+            rear?.next = node
+            rear = node
+        }
+        _size += 1
+    }
+
+    /* 出队 */
+    @discardableResult
+    func poll() -> Int {
+        let num = peek()
+        // 删除头结点
+        front = front?.next
+        _size -= 1
+        return num
+    }
+
+    /* 访问队首元素 */
+    func peek() -> Int {
+        if isEmpty() {
+            fatalError("队列为空")
+        }
+        return front!.val
+    }
+
+    /* 将链表转化为 Array 并返回 */
+    func toArray() -> [Int] {
+        var node = front
+        var res = Array(repeating: 0, count: size())
+        for i in res.indices {
+            res[i] = node!.val
+            node = node?.next
+        }
+        return res
+    }
+}
+
+@main
+enum _LinkedListQueue {
+    /* Driver Code */
+    static func main() {
+        /* 初始化队列 */
+        let queue = LinkedListQueue()
+
+        /* 元素入队 */
+        queue.offer(num: 1)
+        queue.offer(num: 3)
+        queue.offer(num: 2)
+        queue.offer(num: 5)
+        queue.offer(num: 4)
+        print("队列 queue = \(queue.toArray())")
+
+        /* 访问队首元素 */
+        let peek = queue.peek()
+        print("队首元素 peek = \(peek)")
+
+        /* 元素出队 */
+        let poll = queue.poll()
+        print("出队元素 poll = \(poll)，出队后 queue = \(queue.toArray())")
+
+        /* 获取队列的长度 */
+        let size = queue.size()
+        print("队列长度 size = \(size)")
+
+        /* 判断队列是否为空 */
+        let isEmpty = queue.isEmpty()
+        print("队列是否为空 = \(isEmpty)")
+    }
+}

codes/swift/chapter_stack_and_queue/linkedlist_stack.swift

@@ -20,7 +20,7 @@ class LinkedListStack {
 
     /* 判断栈是否为空 */
     func isEmpty() -> Bool {
-        _size == 0
+        size() == 0
     }
 
     /* 入栈 */
@@ -32,6 +32,7 @@ class LinkedListStack {
     }
 
     /* 出栈 */
+    @discardableResult
     func pop() -> Int {
         let num = peek()
         _peek = _peek?.next
@@ -41,7 +42,7 @@ class LinkedListStack {
 
     /* 访问栈顶元素 */
     func peek() -> Int {
-        if _size == 0 {
+        if isEmpty() {
             fatalError("栈为空")
         }
         return _peek!.val

codes/swift/chapter_stack_and_queue/queue.swift

@@ -0,0 +1,39 @@
+/**
+ * File: queue.swift
+ * Created Time: 2023-01-11
+ * Author: nuomi1 (nuomi1@qq.com)
+ */
+
+@main
+enum Queue {
+    /* Driver Code */
+    static func main() {
+        /* 初始化队列 */
+        // Swift 没有内置的队列类，可以把 Array 当作队列来使用
+        var queue: [Int] = []
+
+        /* 元素入队 */
+        queue.append(1)
+        queue.append(3)
+        queue.append(2)
+        queue.append(5)
+        queue.append(4)
+        print("队列 queue = \(queue)")
+
+        /* 访问队首元素 */
+        let peek = queue.first!
+        print("队首元素 peek = \(peek)")
+
+        /* 元素出队 */
+        let pool = queue.removeFirst()
+        print("出队元素 poll = \(pool)，出队后 queue = \(queue)")
+
+        /* 获取队列的长度 */
+        let size = queue.count
+        print("队列长度 size = \(size)")
+
+        /* 判断队列是否为空 */
+        let isEmpty = queue.isEmpty
+        print("队列是否为空 = \(isEmpty)")
+    }
+}

docs/chapter_stack_and_queue/queue.md

@@ -231,7 +231,28 @@ comments: true
 === "Swift"
 
     ```swift title="queue.swift"
+    /* 初始化队列 */
+    // Swift 没有内置的队列类，可以把 Array 当作队列来使用
+    var queue: [Int] = []
 
+    /* 元素入队 */
+    queue.append(1)
+    queue.append(3)
+    queue.append(2)
+    queue.append(5)
+    queue.append(4)
+
+    /* 访问队首元素 */
+    let peek = queue.first!
+
+    /* 元素出队 */
+    let pool = queue.removeFirst()
+
+    /* 获取队列的长度 */
+    let size = queue.count
+
+    /* 判断队列是否为空 */
+    let isEmpty = queue.isEmpty
     ```
 
 ## 队列实现
@@ -627,7 +648,59 @@ comments: true
 === "Swift"
 
     ```swift title="linkedlist_queue.swift"
+    /* 基于链表实现的队列 */
+    class LinkedListQueue {
+        private var front: ListNode? // 头结点
+        private var rear: ListNode? // 尾结点
+        private var _size = 0
 
+        init() {}
+
+        /* 获取队列的长度 */
+        func size() -> Int {
+            _size
+        }
+
+        /* 判断队列是否为空 */
+        func isEmpty() -> Bool {
+            size() == 0
+        }
+
+        /* 入队 */
+        func offer(num: Int) {
+            // 尾结点后添加 num
+            let node = ListNode(x: num)
+            // 如果队列为空，则令头、尾结点都指向该结点
+            if front == nil {
+                front = node
+                rear = node
+            }
+            // 如果队列不为空，则将该结点添加到尾结点后
+            else {
+                rear?.next = node
+                rear = node
+            }
+            _size += 1
+        }
+
+        /* 出队 */
+        @discardableResult
+        func poll() -> Int {
+            let num = peek()
+            // 删除头结点
+            front = front?.next
+            _size -= 1
+            return num
+        }
+
+        /* 访问队首元素 */
+        func peek() -> Int {
+            if isEmpty() {
+                fatalError("队列为空")
+            }
+            return front!.val
+        }
+    }
     ```
 
 ### 基于数组的实现
@@ -1042,7 +1115,63 @@ comments: true
 === "Swift"
 
     ```swift title="array_queue.swift"
+    /* 基于环形数组实现的队列 */
+    class ArrayQueue {
+        private var nums: [Int] // 用于存储队列元素的数组
+        private var front = 0 // 头指针，指向队首
+        private var rear = 0 // 尾指针，指向队尾 + 1
 
+        init(capacity: Int) {
+            // 初始化数组
+            nums = Array(repeating: 0, count: capacity)
+        }
+
+        /* 获取队列的容量 */
+        func capacity() -> Int {
+            nums.count
+        }
+
+        /* 获取队列的长度 */
+        func size() -> Int {
+            let capacity = capacity()
+            // 由于将数组看作为环形，可能 rear < front ，因此需要取余数
+            return (capacity + rear - front) % capacity
+        }
+
+        /* 判断队列是否为空 */
+        func isEmpty() -> Bool {
+            rear - front == 0
+        }
+
+        /* 入队 */
+        func offer(num: Int) {
+            if size() == capacity() {
+                print("队列已满")
+                return
+            }
+            // 尾结点后添加 num
+            nums[rear] = num
+            // 尾指针向后移动一位，越过尾部后返回到数组头部
+            rear = (rear + 1) % capacity()
+        }
+
+        /* 出队 */
+        @discardableResult
+        func poll() -> Int {
+            let num = peek()
+            // 队头指针向后移动一位，若越过尾部则返回到数组头部
+            front = (front + 1) % capacity()
+            return num
+        }
+
+        /* 访问队首元素 */
+        func peek() -> Int {
+            if isEmpty() {
+                fatalError("队列为空")
+            }
+            return nums[front]
+        }
+    }
     ```
 
 ## 队列典型应用

docs/chapter_stack_and_queue/stack.md

@@ -641,7 +641,7 @@ comments: true
 
         /* 判断栈是否为空 */
         func isEmpty() -> Bool {
-            _size == 0
+            size() == 0
         }
 
         /* 入栈 */
@@ -653,6 +653,7 @@ comments: true
         }
 
         /* 出栈 */
+        @discardableResult
         func pop() -> Int {
             let num = peek()
             _peek = _peek?.next
@@ -662,22 +663,11 @@ comments: true
 
         /* 访问栈顶元素 */
         func peek() -> Int {
-            if _size == 0 {
+            if isEmpty() {
                 fatalError("栈为空")
             }
             return _peek!.val
         }
-
-        /* 将 List 转化为 Array 并返回 */
-        func toArray() -> [Int] {
-            var node = _peek
-            var res = Array(repeating: 0, count: _size)
-            for i in sequence(first: res.count - 1, next: { $0 >= 0 + 1 ? $0 - 1 : nil }) {
-                res[i] = node!.val
-                node = node?.next
-            }
-            return res
-        }
     }
     ```
 
@@ -994,8 +984,9 @@ comments: true
         }
 
         /* 出栈 */
+        @discardableResult
         func pop() -> Int {
-            if stack.isEmpty {
+            if isEmpty() {
                 fatalError("栈为空")
             }
             return stack.removeLast()
@@ -1003,16 +994,11 @@ comments: true
 
         /* 访问栈顶元素 */
         func peek() -> Int {
-            if stack.isEmpty {
+            if isEmpty() {
                 fatalError("栈为空")
             }
             return stack.last!
         }
-
-        /* 将 List 转化为 Array 并返回 */
-        func toArray() -> [Int] {
-            stack
-        }
     }
     ```