Is it possible to implement the copy-on-write concept for a linked list?

Yes, the copy-on-write (COW) concept can be implemented for a linked list, although it is not trivial.

The idea of COW is that multiple objects can share the same data until a modification is needed — then a copy of the data is made so that changes do not affect other objects.

For a linked list, this can be done, for example, as follows:

• Each node in the list contains a reference to the next node and a reference count (or a reference counting mechanism).
• When copying the list, a new object is created that references the same nodes, increasing the reference counts.
• When attempting to modify a node, the reference count is checked; if it is greater than 1, a copy of the node (and possibly subsequent nodes) is made so that changes do not affect other lists.

In Swift, for example, standard collections use COW for performance optimization. For custom linked list implementations, you need to manually manage copying and references to ensure correct COW behavior.