Is it possible to have an unordered map consisting of a structure that has an expanding linked list?

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Yes, it is possible to have an unordered map consisting of a structure that has an expanding linked list. In this case, the structure would need to have a pointer to the head of the linked list, and each node in the linked list would need to have a pointer to the next node. As new elements are added to the unordered map, the linked list for that element would be expanded to accommodate the new data. This type of data structure would be useful in situations where the amount of data being stored is not known ahead of time and can potentially grow over time.