c# - 字典、哈希集的访问时间

Question

什么是访问时间:

1. 在字典中查找一个值
2. 检查一个HashSet是否有值

它是不是像 C++0x 的 unordered_map 那样复杂度为 O(1)？

Answer 1

是的，当您使用 Contains 方法或 Dictionary 的索引器时。

来自文档:

The Dictionary(Of TKey, TValue) generic class provides a mapping from a set of keys to a set of values. Each addition to the dictionary consists of a value and its associated key. Retrieving a value by using its key is very fast, close to O(1), because the Dictionary(Of TKey, TValue) class is implemented as a hash table.

http://msdn.microsoft.com/en-us/library/xfhwa508.aspx