partition

partial_sort

template <class RandIter>    void partial_sort(RandIter start, RandIter mid, RandIter end); template <class RandIter, class Comp>     void partial_sort(RandIter start, RandIter mid,                       RandIter end, Comp cmpfn);

The partial_sort( ) algorithm sorts the range start to end. However, after execution, only elements in the range start to mid will be in sorted order.

The second form allows you to specify a comparison function that determines when one element is less than another.