什么 .NET 集合提供最快的搜索

问题描述

我有 60k 项需要对照 20k 查找列表进行检查.是否有一个集合对象(如 List、HashTable)提供了一个异常快速的 Contains() 方法?还是我必须自己写?换句话说，默认的 Contains() 方法是只扫描每个项目还是使用更好的搜索算法.

I have 60k items that need to be checked against a 20k lookup list. Is there a collection object (like List, HashTable) that provides an exceptionly fast Contains() method? Or will I have to write my own? In otherwords, is the default Contains() method just scan each item or does it use a better search algorithm.

foreach (Record item in LargeCollection)
{
    if (LookupCollection.Contains(item.Key))
    {
       // Do something
    }
}

注意.查找列表已经排序.

推荐答案

在最一般的情况下，考虑 System.Collections.Generic.HashSet 作为默认的包含"主力数据结构，因为评估 Contains 需要恒定的时间.

In the most general case, consider System.Collections.Generic.HashSet as your default "Contains" workhorse data structure, because it takes constant time to evaluate Contains.

什么是最快的可搜索集合"的实际答案取决于您的特定数据大小、有序性、散列成本和搜索频率.

The actual answer to "What is the fastest searchable collection" depends on your specific data size, ordered-ness, cost-of-hashing, and search frequency.

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