C# 數據結構與算法系列(五) 隊列

隊列是一種特殊的線性表，它只允許在表的前端（front）進行刪除操作，而在表的後端（back）進行插入操作。進行插入操作的端稱為隊尾，進行刪除操作的端稱為隊頭。這也就是我們平常經常用說到的先進先出法則（FIFO），隊列這種法則，在中國好久以前就開始運用了，例如糧倉管理官員，在沒掌握這種法則前，倉庫底部的糧食都因時間太久而壞掉了，後來有聰明人士在糧倉二邊開個門，一邊進倉一邊出倉，這樣管理就方便多了。隊列中沒有元素時，稱為空隊列。
隊列實現的接口如下：
    public interface IQueen<T>
    {
        int Length();
        bool IsEmpty();
        bool IsFull();
        void Clear();
        void IN(T items);
        T Out();
        T GetFrontItem();
    }隊列實現的原理與代碼如下： Code
    public class JQueen<T> : IQueen<T>
    {
        private int size;
        private T[] item;
        private int front;
        private int back;

        public JQueen()
            : this(100)
        {
            size = 100;
            item = new T[100];
            front = back = -1;
        }

        public JQueen(int length)
        {
            size = length;
            item = new T[length];
            front = back = -1;
        }

        public T this[int index]
        {
            get { return item[index]; }
            set { item[index] = value; }
        }

        public int Front
        {
            get { return front; }
            set { front = value; }           
        }

        public int Back
        {
            get { return back; }
            set { back = value; }
        }

        public int MaxLength
        {
            get { return size; }
            set { size = value; }
        }       

        public int Length()
        {
            return (back - front + size) % size;
        }

        public bool IsEmpty()
        {
            return (front == back);
        }

        public bool IsFull()
        {
            return ((back + 1) % size == front);
        }

        public void Clear()
        {
            front = back = -1;
        }

        public void IN(T items)
        {
            if (IsFull())
            {
                throw new ArgumentOutOfRangeException("RangeException", "Queen RangeException: queen is full");
            }
            item[++back] = items;
        }

        public T Out()
        {
            T tmp = default(T);
            if (IsEmpty())
            {
                throw new ArgumentOutOfRangeException("RangeException", "Queen RangeException: queen is empty");
            }
            tmp = item[++front];
            return tmp;
        }

        public T GetFrontItem()
        {
            if (IsEmpty())
            {
                throw new ArgumentOutOfRangeException("RangeException", "Queen RangeException: queen is empty");
            }
            return item[front + 1];
        }

    }
測試隊列代碼：

Code
    public class Program
    {
        static void Main(string[] args)
        {
            try
            {
                JQueen<string> JQ = new JQueen<string>();
                Console.WriteLine(JQ.IsEmpty());  //是否為空
                Console.WriteLine(JQ.IsFull());   //是否滿隊
     &n