cpp/algorithm/ranges/partial sort copy

Copies the first elements from the source range, as if it was partially sorted with respect to  and , into the destination range , where ,  is equal to , and  is equal to.

The order of equal elements is not guaranteed to be preserved.

@1@ The source range elements are projected using the function object, and the destination elements are projected using the function object.

@2@ Same as, but uses as the source range and  as the destination range, as if using  as ,  as ,  as , and  as.

Return value
An object equal to.

Complexity
At most comparisons and  projections.