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You can store non-copyable, non-movable objects in an
unordered_set.Finding whether a given element is in the set is O(1) instead of O(n), or O(log n) if you keep the vector sorted (which is itself O(n) on insertion).
unordered_setdisallows duplicates.Removing a given element is O(1). In the case of a sorted vector, it’s O(n).
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solved Reasons for preferring unorder_set to a vector