LinkedList vs List<T> [duplicate]

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When should I use a List vs a LinkedList

If I expect not to use the access by index for my data structure how much do I save by using 开发者_如何学运维 LinkedList over List ? If if am not 100% sure I will never use access by index, I would like to know the difference.

Suppose I have N instances. inserting and removing in a LinkedList will only be a o(1) op , where as in List it may me be O(n), but since it it optimized, it would be nice to know what the difference is for some values of n. say N = 1,000,000 and N = 1,000,000,000

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List<T> is just a wrapper over an Array. LinkedList<T> is only at it's most efficient if you are accessing sequential data (either forwards or backwards).

Linked lists provide very fast insertion or deletion of a list member. Each member in a linked list contains a pointer to the next member in the list so to insert a member at position i:

update the pointer in member i-1 to point to the new member
set the pointer in the new member to point to member i

Check this: When should I use a List vs a LinkedList

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LinkedList<T> is useful if you perform many random insertions and deletions of items in your list. Otherwise a List<T> is probably the best choice as it carries no overhead for linking the elements in the list (and also can be indexed).

However, if you are concerned about performance you really need to test your actual code.