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

namespace QueueTest
{
    public struct pqItem {
        public int priority;
        public string name;
    }
    /// <summary>
    /// 源自Queue的优先队列
    /// </summary>
    class PQueue:Queue
    {
        public PQueue() {


        }
        /// <summary>
        /// 重写出队
        /// </summary>
        /// <returns></returns>
        public override object Dequeue()
        {
            object[] items;//数组
            int min;//数字越小优先级越大
            items = this.ToArray();//队列元素复制到数组
            min = ((pqItem)items[0]).priority;//默认数组索引为0的优先级最大
            //
            for (int i = 0; i <= items.GetUpperBound(0); i++)            
                if (((pqItem)items[i]).priority<min)
                {
                    min = ((pqItem)items[i]).priority;//优先级重新设置
                }

                this.Clear();//从队列中移除所有对象
                int x2;
            //对数组循环遍历
                for (x2 = 0; x2 < items.GetUpperBound(0); x2++)
               //如果数组中找到优先级最高的（且名字不为空） 就进队 
                    if (((pqItem)items[x2]).priority ==min&&((pqItem)items[x2]).name!="")                    
                        this.Enqueue(items[x2]); //进队 
            Console.WriteLine(this.Count); //值为1                                      
            return base.Dequeue();//先进先出
        }

        static void Main() {
            PQueue erwait = new PQueue();//创建一个队列
            pqItem[] erPatient = new pqItem[3];//创建pqItem的数组

            pqItem nextPatient;//下一个
            erPatient[0].name = "Joe Smith";
            erPatient[0].priority = 1;

            erPatient[1].name = "Mary Smith";
            erPatient[1].priority = 0;

            erPatient[2].name = "Sam Smith";
            erPatient[2].priority = 3;

            for (int i = 0; i <= erPatient.GetUpperBound(0); i++)
            {
                erwait.Enqueue(erPatient[i]);
            }
            Console.WriteLine(erwait.Count);//值为3 
            nextPatient =(pqItem)erwait.Dequeue();
            Console.WriteLine(erwait.Count);//值为0 
            Console.WriteLine(nextPatient.name);
            Console.Read();

        }
    }
}