Runtime Complexity of .NET Generic Collection

Runtime Complexity of .NET Generic Collection

 

I had to implement some data structures for my computational geometry class. Deciding whether to implement the data structures myself or using the build-in classes turned out to be a hard decision, as the runtime complexity information is located at the method itself, if present at all. So I went ahead to consolidate all the information in one table, then looked at the source code in Reflector and verified them. Below is my result.

	Internal Implement-  ation	Add/insert	Add beyond capacity	Queue/Push	Dequeue/ Pop/Peek	Remove/  RemoveAt	Item[i]/Find(i)	GetEnumerator	MoveNext
List	Array	O(1) to add, O(n) to insert	O(n)	-	-	O(n)	O(1)	O(1)	O(1)
LinkedList	Doubly linked list	O(1), before/after given node	O(1)	O(1)	O(1)	O(1), before/after given node	O(n)	O(1)	O(1)
Stack	Array	O(1)	O(n)	O(1)	O(1)	-	-	O(1)	O(1)
Queue	Array	O(1)	O(n)	O(1)	O(1)	-	-	O(1)	O(1)
Dictionary	Hashtable with links to another array index for collision	O(1), O(n) if collision	O(n)	-	-	O(1), O(n) if collision	O(1), O(n) if collision	O(1)	O(1)
HashSet	Hashtable with links to another array index for collision	O(1), O(n) if collision	O(n)	-	-	O(1), O(n) if collision	O(1), O(n) if collision	O(1)	O(1)
SortedDictionary	Red-black tree	O(log n)	O(log n)	-	-	O(log n)	O(log n)	O(log n)	O(1)
SortedList	Array	O(n)	O(n)	-	-	O(n)	O(1)	O(1)	O(1)
SortedSet	Red-black tree	O(log n)	O(log n)	-	-	O(log n)	O(log n)	O(log n)	O(1)

Note:

Dictionary	Add, remove and item[i] has expected O(1) running time
HashSet	Add, remove and item[i] has expected O(1) running time

 

http://c-sharp-snippets.blogspot.com/2010/03/runtime-complexity-of-net-generic.html