.NET中的堆类 [英] Heap class in .NET
问题描述
可能重复:
C#中的斐波那契,二进制或二项式堆?
.NET中是否有类似堆的类? 我需要一些可以从中检索分钟的集合.元素.我只想要3种方法:
Is there any class like heap in .NET? I need some kind of collection from which I can retrieve min. element. I just want 3 methods:
-
Add()
-
RemoveMinElement()
-
GetMinElement()
Add()
RemoveMinElement()
GetMinElement()
我不能使用排序列表,因为那里的键必须是唯一的,而且我可能有几个相同的元素.
I can't use sorted list because there keys has to be unique, and I might have several identical elements.
推荐答案
您可以使用 SortedDictionary
(请参见下面的讨论).如果您使用的是具有引用相等性的类型,但是可以根据您关心的值进行比较,则可以使用这种方法.
You could use SortedList
or a SortedDictionary
(see discussion below) with a custom key. If you used a type with referential equality, but could be compared based on the value you care about, then this could work.
类似这样的东西:
class HeapKey : IComparable<HeapKey>
{
public HeapKey(Guid id, Int32 value)
{
Id = id;
Value = value;
}
public Guid Id { get; private set; }
public Int32 Value { get; private set; }
public int CompareTo(HeapKey other)
{
if (_enableCompareCount)
{
++_compareCount;
}
if (other == null)
{
throw new ArgumentNullException("other");
}
var result = Value.CompareTo(other.Value);
return result == 0 ? Id.CompareTo(other.Id) : result;
}
}
这是使用具有二进制堆性能特征的SortedDictionary
的有效示例:
Here is a working example of using a SortedDictionary
which has binary-heap performance characteristics:
using System;
using System.Collections.Generic;
using System.Linq;
namespace SortedDictionaryAsBinaryHeap
{
class Program
{
private static Boolean _enableCompareCount = false;
private static Int32 _compareCount = 0;
static void Main(string[] args)
{
var rnd = new Random();
for (int elementCount = 2; elementCount <= 6; elementCount++)
{
var keyValues = Enumerable.Range(0, (Int32)Math.Pow(10, elementCount))
.Select(i => new HeapKey(Guid.NewGuid(), rnd.Next(0, 10)))
.ToDictionary(k => k);
var heap = new SortedDictionary<HeapKey, HeapKey>(keyValues);
_compareCount = 0;
_enableCompareCount = true;
var min = heap.First().Key;
_enableCompareCount = false;
Console.WriteLine("Element count: {0}; Compare count for getMinElement: {1}",
(Int32)Math.Pow(10, elementCount),
_compareCount);
_compareCount = 0;
_enableCompareCount = true;
heap.Remove(min);
_enableCompareCount = false;
Console.WriteLine("Element count: {0}; Compare count for deleteMinElement: {1}",
(Int32)Math.Pow(10, elementCount),
_compareCount);
}
Console.ReadKey();
}
private class HeapKey : IComparable<HeapKey>
{
public HeapKey(Guid id, Int32 value)
{
Id = id;
Value = value;
}
public Guid Id { get; private set; }
public Int32 Value { get; private set; }
public int CompareTo(HeapKey other)
{
if (_enableCompareCount)
{
++_compareCount;
}
if (other == null)
{
throw new ArgumentNullException("other");
}
var result = Value.CompareTo(other.Value);
return result == 0 ? Id.CompareTo(other.Id) : result;
}
}
}
}
结果:
元素数:100;比较getMinElement的计数:0
Element count: 100; Compare count for getMinElement: 0
元素数:100;比较deleteMinElement的计数:8
Element count: 100; Compare count for deleteMinElement: 8
元素数:1000;比较getMinElement的计数:0
Element count: 1000; Compare count for getMinElement: 0
元素数:1000;比较deleteMinElement的计数:10
Element count: 1000; Compare count for deleteMinElement: 10
元素数:10000;比较getMinElement的计数:0
Element count: 10000; Compare count for getMinElement: 0
元素数:10000;比较deleteMinElement的计数:13
Element count: 10000; Compare count for deleteMinElement: 13
元素数:100000;比较getMinElement的计数:0
Element count: 100000; Compare count for getMinElement: 0
元素数:100000;比较deleteMinElement的计数:14
Element count: 100000; Compare count for deleteMinElement: 14
元素数:1000000;比较getMinElement的计数:0
Element count: 1000000; Compare count for getMinElement: 0
元素数:1000000;比较deleteMinElement的计数:21
Element count: 1000000; Compare count for deleteMinElement: 21
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