C#数据结构与算法系列（三）：队列（Queue）

    public class CircleArrayQueue
    {
        /// 

        /// 队列最大值
        /// 
        public int MaxSize { get; set; }

        /// 

        /// 队列头部
        /// 
        public int Front { get; set; }

        /// 

        /// 队列尾部
        /// 
        public int Rear { get; set; }

        /// 

        /// 队列数组
        /// 
        public int[] Arr { get; set; }

        /// 

        /// 构造函数初始化队列
        /// 
        /// 
        public CircleArrayQueue(int maxSize)
        {
            this.MaxSize = maxSize+1;
            Arr = new int[MaxSize];
            //Front = 0;
            //Rear = 0; 默认值
        }

        /// 

        /// 判断队列是否为满；当尾索引的下一个为头索引时表示队列满，将队列容量空出一个作为约定
        /// 
        /// 
        public bool IsFull() => (Rear + 1) % MaxSize==Front; 

       /// 

       /// 判断队列是否为空；当队列首==队列尾 首尾相等
       /// 
       /// 
        public bool IsEmpty() => Front == Rear;

        public void AddQueue(int value)
        {
            if (IsFull()) Console.WriteLine("队列已满！不能再添加数据");
            else
            {
                //直接将数据加入
                Arr[Rear] = value;
                //将队列尾部后移一个位置，因为是环形数组队列要考虑取模
                Rear = (Rear + 1) % MaxSize;
            }
        }

        public void ShowQueue()
        {
            if (IsEmpty()) Console.WriteLine("队列为空！没有数据");
            else
            {
                //从Front开始遍历
                for (int i = Front; i )
                {
                    Console.WriteLine($"Arr[{i%MaxSize}]={Arr[i%MaxSize]}");
                }
            }
        }

        /// 

        /// 队列尾 + 最大值 - 队列首 % 最大值
        /// 
        /// 
        public int Size() => (Rear + MaxSize-Front) % MaxSize;

        /// 

        /// 取出队列数据
        /// 
        /// 
        public int GetQueue()
        {
            if (IsEmpty()) throw new Exception("队列为空！没有数据");
            //1.先把Front对应的值保留到一个临时变量
            //2.重新分配Front的值，将Front后移，要考虑取模
            //3.将临时变量返回
            var val = Arr[Front];
            Front = (Front + 1) % MaxSize;
            return val;
        }

        public int HeadQueue()
        {
            if (IsEmpty()) throw new Exception("队列为空！没有数据");
            //直接返回头元素
            return Arr[Front];
        }

        public static void Test()
        {
            CircleArrayQueue queue = new CircleArrayQueue(3);
            string key = "";
            bool loop = true;
            while (loop)
            {
                Console.WriteLine("s(show):显示队列");
                Console.WriteLine("e(exit):退出程序");
                Console.WriteLine("a(add):添加数据到队列队列");
                Console.WriteLine("g(get):从队列中取出数据");
                Console.WriteLine("h(head):查看队列头部的数据");
                key = Console.ReadLine();
                switch (key)
                {
                    case "s":
                        queue.ShowQueue();
                        break;
                    case "a":
                        Console.WriteLine("请输入一个值");
                        int.TryParse(Console.ReadLine(), out int value);
                        queue.AddQueue(value);
                        break;
                    case "g":
                        try
                        {
                            int reuslt = queue.GetQueue();
                            Console.WriteLine("取出来的数据：" + reuslt);
                        }
                        catch (Exception ex)
                        {
                            Console.WriteLine(ex.Message);
                        }
                        break;
                    case "h":
                        try
                        {
                            int reuslt = queue.HeadQueue();
                            Console.WriteLine("队列头的数据：" + reuslt);
                        }
                        catch (Exception ex)
                        {
                            Console.WriteLine(ex.Message);
                        }
                        break;
                    case "e":
                        loop = false;
                        break;
                    default:
                        break;
                }
            }
            Console.WriteLine("程序退出");
        }

    }