c# - OrderedDictionary 的复杂性是什么？

Question

没有人说 OrderedDictionary 有两个元素副本，一个在哈希表中，另一个在列表中，我在 MSDN 上找不到 OrderedList 的复杂性度量。

谢谢

Answer 1

看看

OrderedDictionary: A generic implementation of IOrderedDictionary

This implementation of an ordered dictionary is very good at lookup operations: the array allows O(1) lookups by index, and the hashtable allows O(1) lookups by key. However, the necessity of keeping the array synchronized with the hashtable means that insert/delete operations have the performance disadvantage of performing those operations on an array (O(n) at worst). There is also, of course, the extra memory requirement of storing both data structures. Because of these disadvantages, OrderedDictionary should only be used when insert/delete operations will be minimal and there is a need to efficiently access elements by index and/or key.