24 Containers library [containers]

24.6 Container adaptors [container.adaptors]

24.6.10 Class template flat_multimap [flat.multimap]

24.6.10.3 Constructors [flat.multimap.cons]

flat_multimap(key_container_type key_cont, mapped_container_type mapped_cont, const key_compare& comp = key_compare());
Effects: Initializes c.keys with std​::​move(key_cont), c.values with std​::​move(mapped_cont), and compare with comp; sorts the range [begin(), end()) with respect to value_comp().
Complexity: Linear in N if the container arguments are already sorted with respect to value_comp() and otherwise , where N is the value of key_cont.size() before this call.
flat_multimap(sorted_equivalent_t, key_container_type key_cont, mapped_container_type mapped_cont, const key_compare& comp = key_compare());
Effects: Initializes c.keys with std​::​move(key_cont), c.values with std​::​move(mapped_cont), and compare with comp.
Complexity: Constant.