# 25 Algorithms library [algorithms]

## 25.4 Sorting and related operations [alg.sorting]

### 25.4.1 Sorting [alg.sort]

#### 25.4.1.1sort[sort]

``` template<class RandomAccessIterator> void sort(RandomAccessIterator first, RandomAccessIterator last); template<class RandomAccessIterator, class Compare> void sort(RandomAccessIterator first, RandomAccessIterator last, Compare comp); ```

Effects: Sorts the elements in the range [first,last).

Requires: RandomAccessIterator shall satisfy the requirements of ValueSwappable ([swappable.requirements]). The type of *first shall satisfy the requirements of MoveConstructible (Table [moveconstructible]) and of MoveAssignable (Table [moveassignable]).

Complexity: Ο(Nlog(N)) (where N == last - first) comparisons.

#### 25.4.1.2stable_sort[stable.sort]

``` template<class RandomAccessIterator> void stable_sort(RandomAccessIterator first, RandomAccessIterator last); template<class RandomAccessIterator, class Compare> void stable_sort(RandomAccessIterator first, RandomAccessIterator last, Compare comp); ```

Effects: Sorts the elements in the range [first,last).

Requires: RandomAccessIterator shall satisfy the requirements of ValueSwappable ([swappable.requirements]). The type of *first shall satisfy the requirements of MoveConstructible (Table [moveconstructible]) and of MoveAssignable (Table [moveassignable]).

Complexity: It does at most N log2(N) (where N == last - first) comparisons; if enough extra memory is available, it is N log(N).

Remarks: Stable ([algorithm.stable]).

#### 25.4.1.3partial_sort[partial.sort]

``` template<class RandomAccessIterator> void partial_sort(RandomAccessIterator first, RandomAccessIterator middle, RandomAccessIterator last); template<class RandomAccessIterator, class Compare> void partial_sort(RandomAccessIterator first, RandomAccessIterator middle, RandomAccessIterator last, Compare comp); ```

Effects: Places the first middle - first sorted elements from the range [first,last) into the range [first,middle). The rest of the elements in the range [middle,last) are placed in an unspecified order.

Requires: RandomAccessIterator shall satisfy the requirements of ValueSwappable ([swappable.requirements]). The type of *first shall satisfy the requirements of MoveConstructible (Table [moveconstructible]) and of MoveAssignable (Table [moveassignable]).

Complexity: It takes approximately (last - first) * log(middle - first) comparisons.

#### 25.4.1.4partial_sort_copy[partial.sort.copy]

``` template<class InputIterator, class RandomAccessIterator> RandomAccessIterator partial_sort_copy(InputIterator first, InputIterator last, RandomAccessIterator result_first, RandomAccessIterator result_last); template<class InputIterator, class RandomAccessIterator, class Compare> RandomAccessIterator partial_sort_copy(InputIterator first, InputIterator last, RandomAccessIterator result_first, RandomAccessIterator result_last, Compare comp); ```

Effects: Places the first min(last - first, result_last - result_first) sorted elements into the range [result_first,result_first + min(last - first, result_last - result_first)).

Returns: The smaller of: result_last or result_first + (last - first).

Requires: RandomAccessIterator shall satisfy the requirements of ValueSwappable ([swappable.requirements]). The type of *result_first shall satisfy the requirements of MoveConstructible (Table [moveconstructible]) and of MoveAssignable (Table [moveassignable]).

Complexity: Approximately (last - first) * log(min(last - first, result_last - result_first)) comparisons.

#### 25.4.1.5is_sorted[is.sorted]

``` template<class ForwardIterator> bool is_sorted(ForwardIterator first, ForwardIterator last); ```

Returns: is_sorted_until(first, last) == last

``` template<class ForwardIterator, class Compare> bool is_sorted(ForwardIterator first, ForwardIterator last, Compare comp); ```

Returns: is_sorted_until(first, last, comp) == last

``` template<class ForwardIterator> ForwardIterator is_sorted_until(ForwardIterator first, ForwardIterator last); template<class ForwardIterator, class Compare> ForwardIterator is_sorted_until(ForwardIterator first, ForwardIterator last, Compare comp); ```

Returns: If distance(first, last) < 2, returns last. Otherwise, returns the last iterator i in [first,last] for which the range [first,i) is sorted.

Complexity: Linear.