数据结构-循环顺序队列&链队列

队列接口实现：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _003_队列
{
    interface IQueue<T>
    {
        int Count { get; }
        int GetLength();
        bool IsEmpty();
        void Clear();
        void Enqueue(T item);
        T Dequeue();
        T Peek();
    }
}

顺序循环队列实现：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _003_队列
{
    /// <summary>
    /// 顺序队列
    /// </summary>
    /// <typeparam name="T"></typeparam>
    class SeqQueue<T> : IQueue<T>
    {
        private T[] data;
        private int count;//当前元素数量
        private int front;//队首 (队首元素索引-1)
        private int rear;//队尾 （队尾元素索引）
        public SeqQueue(int size)
        {
            data = new T[size];
            count = 0;
            front = -1;
            rear = -1;
        }
        public SeqQueue() : this(10) { }
        public int Count
        {
            get
            {
                return count;
            }
        }
        public void Clear()
        {
            count = 0;
            front = rear = -1;
           
        }
        public int GetLength()
        {
            return count;
        }
        public bool IsEmpty()
        {
            return count == 0;
        }

        /// <summary>
        /// 出队,并删除数据
        /// </summary>
        /// <returns></returns>
        public T Dequeue()
        {
            if (!IsEmpty())
            {
                T temp = data[front + 1];
                front++;
                count--;
                return temp;
            }
            else
            {
                Console.WriteLine("队列为空");
                return default(T);
            }
        }
        /// <summary>
        /// 入队
        /// </summary>
        /// <param name="item"></param>
        public void Enqueue(T item)
        {
            if (count == data.Length)
            {
                Console.WriteLine("队列已满，不可以再添加新的数据");
            }
            else
            {
                if (rear == data.Length - 1) //判断是否在尾部，是就把元素放在0位置
                {
                    data[0] = item;
                    rear = 0;
                }
                else//不是就继续添加
                {
                    data[rear + 1] = item;
                    rear++;
                }
                count++;
            }
        }

        //取得队首数据
        public T Peek()
        {
            if (IsEmpty())
            {
                return default(T);
            }
            else
            {
                return data[front + 1];
            }
        }
    }
}

链结点：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _003_队列
{
    class Node<T>
    {
        private T data;
        private Node<T> next;
        public Node(T data)
        {
            this.data = data;
        }
        public T Data
        {
            get
            {
                return data;
            }
            set
            {
                data = value;
            }
        }
        public Node<T> Next
        {
            get
            {
                return next;
            }
            set
            {
                next = value;
            }
        }
    }
}

链队列实现：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _003_队列
{
    /// <summary>
    /// 链队列
    /// </summary>
    /// <typeparam name="T"></typeparam>
    class LinkQueue<T> : IQueue<T>
    {
        private Node<T> front;
        private Node<T> rear;
        private int count; //元素个数


        public LinkQueue()
        {
            front = null;
            rear = null;
            count = 0;
        }
        public int Count
        {
            get
            {
                return count;
            }
        }
        public int GetLength()
        {
            return count;
        }
        public bool IsEmpty()
        {
            return count == 0;
        }
        public void Clear()
        {
            count = 0;
            front = null;
            rear = null;
        }

        /// <summary>
        /// 出队
        /// </summary>
        /// <returns></returns>
        public T Dequeue()
        {
            if (IsEmpty())
            {
                Console.WriteLine("队列为空,无法出队");
                return default(T);
            }
            else if (count == 1) //等于1  说明 头和尾一样
            {
                T temp = front.Data;
                front = rear = null;
                count = 0;
                return temp;
            }
            else //直接删除头 头变成下一个结点
            {
                T temp = front.Data;
                front = front.Next;
                count--;
                return temp;
            }
        }


        /// <summary>
        /// 入队
        /// </summary>
        /// <param name="item"></param>
        public void Enqueue(T item)
        {
                Node<T> newNode = new Node<T>(item);
                if (IsEmpty())
                {
                    front =rear = newNode;
                }
                else
                {
                    rear.Next = newNode;
                    rear = newNode;
                }
                count++;
        }

        public T Peek()
        {
            if (front!=null)
            {
                return front.Data;
            }
            else
            {
                return default(T);
            }
        }
        
    }
}

栈和队列的应用

       /// <summary>
        /// 使用栈和队列 判断是否为回文
        /// </summary>
        /// <returns></returns>
        public static bool IsPalindrome(string temp)
        {
            Stack<char> stack = new Stack<char>();//先进后出
            LinkQueue<char> queue = new LinkQueue<char>();//先进先出

            string str = temp;
            //进栈 进队
            for (int i = 0; i < str.Length; i++)
            {
                stack.Push(str[i]);
                queue.Enqueue(str[i]);    
            }

            //判断前后是否一样
            bool flag = false;
            for (int i = 0; i < str.Length/2; i++)
            {
                if (queue.Dequeue() == stack.Pop())
                {
                    flag = true;
                }
                else
                {
                    flag = false;
                }
            }
            return flag;
        }

        /// <summary>
        /// 变大写
        /// </summary>
        /// <param name="s"></param>
        public static void ToUpper(string s)
        {
            Queue<char> que = new Queue<char>();
            char w;
            for (int i = 0; i < s.Length; i++)
            {
              if(s[i] > 96 && s[i] < 123)
                {
                    w = Convert.ToChar(s[i] - 32);
                }
               else
                {
                    w = s[i];
                }           
                que.Enqueue(w);
            }
            for (int i = 0; i < s.Length; i++)
            {
                Console.Write(que.Dequeue());
            }
        }
        /// <summary>
        /// 变小写
        /// </summary>
        /// <param name="s"></param>
        public static void ToLower(string s)
        {
            Queue<char> que = new Queue<char>();
            char w;
            for (int i = 0; i < s.Length; i++)
            {
                if (s[i] > 64 && s[i] < 91)
                {
                    w = Convert.ToChar(s[i] + 32);
                }
                else
                {
                    w = s[i];
                }
                que.Enqueue(w);
            }
            for (int i = 0; i < s.Length; i++)
            {
                Console.Write(que.Dequeue());
            }
        }