C#用堆实现优先级队列

【int版本】

using System;
using System.Collections.Generic;


namespace MyDS
{
    class PriorityQueue
    {
        private int[] array;
        public int Count { get; private set; }
        private bool isMax;//true表示大顶堆，默认的，false表示小顶堆

        public PriorityQueue(bool isMax=true)
        {
            //初始大小为16
            array=new int[16];
            this.isMax = isMax;
        }

        /// 

        /// 入队
        /// 
        /// 
        public void Enqueue(int key)
        {
            if (Count >= array.Length)
            {
                Resize();
            }
            array[Count++] = key;//将新元素放在队尾
            UpAdjust();//队尾元素破坏了二叉堆，将队尾元素上浮
        }

        /// 

        /// 队首元素出队
        /// 
        /// 
        public int Dequeue()
        {
            if (Count <= 0)
            {
                throw new InvalidOperationException("优先队列为空");
            }
            int head = array[0];
            array[0] = array[--Count];//让最后一个元素移动到堆顶
            DownAdjust();//队首元素破坏了二叉堆，将队首元素下沉
            return head;

        }

        /// 

        /// 获取队首元素
        /// 
        /// 
        public int GetHead()
        {
            if (Count > 0)
                return array[0];
            else
            {
                throw new InvalidOperationException("优先队列为空");
            }
        }

        /// 

        /// 队列是否为空
        /// 
        /// 
        public bool IsEmpty()
        {
            return (Count == 0);
        }

        /// 

        /// 清空队列
        /// 
        public void Clear()
        {
            Count = 0;
        }

        /// 

        /// 判断队列是否包含某元素
        /// 
        /// 
        /// 
        public bool Contains(int key)
        {
            bool contains = false;
            for (int i = 0; i < Count; i++)
            {
                if (array[i] == key)
                {
                    contains = true;
                    break;
                }
            }
            return contains;
        }

        /// 

        /// 上浮
        /// 
        private void UpAdjust()
        {
            int childIndex = Count - 1;
            int parentIndex = (childIndex - 1) >> 1;
            int temp = array[childIndex];
            while (parentIndex >= 0 && (isMax? (temp > array[parentIndex]): (temp < array[parentIndex])))
            {               
                array[childIndex] = array[parentIndex];
                childIndex = parentIndex;
                parentIndex = (childIndex - 1) >> 1;
            }
            array[childIndex] = temp;
        }

        /// 

        /// 下沉
        /// 
        private void DownAdjust()
        {
            int temp = array[0];
            int index = 0;
            for (int i = 1; i < Count; i = 2 * i + 1)
            {
                if (i + 1 < Count && (isMax?( array[i] < array[i + 1]): (array[i] > array[i + 1])))
                {
                    i++;
                }
                if (isMax ? (temp < array[i]): (temp > array[i]))
                {
                    array[index] = array[i];
                    index = i;
                }
                else
                {
                    break;
                }
            }
            array[index] = temp;
        }

        /// 

        /// 扩容
        /// 
        private void Resize()
        {
            int[] newArray=new int[2*array.Length];
            for (int i = 0; i < array.Length; i++)
            {
                newArray[i] = array[i];
            }
            array = newArray;
        }


    }

}