std::nth_element

 

C++

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Libreria di Utilità

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Espressioni regolari(C++11)

Operazioni atomicche(C++11)

Multithreading(C++11)

 

Algoritmo libreria

Funzioni Original: Functions The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
Non modifica le operazioni di sequenza Original: Non-modifying sequence operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
all_of any_of none_of (C++11) (C++11) (C++11) for_each count count_if mismatch equal	find find_if find_if_not (C++11) find_end find_first_of adjacent_find search search_n
Modifica delle operazioni di sequenza Original: Modifying sequence operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
copy copy_if (C++11) copy_n (C++11) copy_backward move (C++11) move_backward (C++11) fill fill_n transform generate generate_n remove remove_if remove_copy remove_copy_if	replace replace_if replace_copy replace_copy_if swap swap_ranges iter_swap reverse reverse_copy rotate rotate_copy random_shuffle shuffle   (C++11) unique unique_copy
Partizionamento operazioni Original: Partitioning operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
is_partitioned (C++11) partition partition_copy (C++11)	stable_partition partition_point (C++11)
Ordinamento delle operazioni (su intervalli ordinati) Original: Sorting operations (on sorted ranges) The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
is_sorted (C++11) is_sorted_until (C++11) sort	partial_sort partial_sort_copy stable_sort nth_element
Binarie (le operazioni di ricerca sui campi ordinati) Original: Binary search operations (on sorted ranges) The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
lower_bound upper_bound	binary_search equal_range
Impostare le operazioni (su intervalli ordinati) Original: Set operations (on sorted ranges) The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
merge inplace_merge includes	set_difference set_intersection set_symmetric_difference set_union
Heap operazioni Original: Heap operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
is_heap is_heap_until (C++11) make_heap	push_heap pop_heap sort_heap
Minimo / massimo le operazioni Original: Minimum/maximum operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
max max_element min min_element minmax (C++11) minmax_element (C++11)	lexicographical_compare is_permutation (C++11) next_permutation prev_permutation
Operazioni numeriche Original: Numeric operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
iota (C++11) accumulate inner_product	adjacent_difference partial_sum
Libreria C Original: C library The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
qsort	bsearch

 

Defined in header <algorithm>
template<class RandomIt > void nth_element( RandomIt first, RandomIt nth, RandomIt last );	(1)
template<class RandomIt, class Compare > void nth_element( RandomIt first, RandomIt nth, RandomIt last, Compare comp );	(2)

Parzialmente ordina la [first, last) intervallo in ordine crescente in modo che tutti gli elementi della gamma [first, nth) sono meno rispetto a quelli del [nth, last) gamma. La prima versione utilizza operator< di confrontare gli elementi, la seconda versione utilizza la data comp funzione di confronto. L'elemento posto in posizione nth è esattamente l'elemento che si verificano in questa posizione se l'intervallo è stato completamente ordinato.

Original:

Partially sorts the range [first, last) in ascending order so that all elements in the range [first, nth) are less than those in the range [nth, last). The first version uses operator< to compare the elements, the second version uses the given comparison function comp. The element placed in the nth position is exactly the element that would occur in this position if the range was fully sorted.

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Parametri

first, last	-	iteratori ad accesso casuale che definiscono il tipo gamma Original: random access iterators defining the range sort The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
nth	-	iteratore ad accesso casuale la definizione del punto di partizione ordinamento Original: random access iterator defining the sort partition point The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
comp	-	comparison function which returns ​true if the first argument is less than the second. The signature of the comparison function should be equivalent to the following:  bool cmp(const Type1 &a, const Type2 &b); The signature does not need to have const&, but the function must not modify the objects passed to it. The types Type1 and Type2 must be such that an object of type RandomIt can be dereferenced and then implicitly converted to both of them. ​
Type requirements
- RandomIt must meet the requirements of ValueSwappable and RandomAccessIterator.
- The type of dereferenced RandomIt must meet the requirements of MoveAssignable and MoveConstructible.

Valore di ritorno

(Nessuno)

Original:

(none)

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Complessità

Lineare in std::distance(first, last) in media.

Original:

Linear in std::distance(first, last) on average.

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Esempio

#include <iostream>#include <vector>#include <algorithm>#include <functional>   int main(){std::vector<int> v{5, 6, 4, 3, 2, 6, 7, 9, 3};   std::nth_element(v.begin(), v.begin()+ v.size()/2, v.end());std::cout<<"The median is "<< v[v.size()/2]<<'\n';   std::nth_element(v.begin(), v.begin()+1, v.end(), std::greater<int>());std::cout<<"The second largest element is "<< v[1]<<'\n';}

Output:

The median is 5 The second largest element is 7

Vedi anche

partial_sort_copy	copie e parzialmente ordina una serie di elementi Original: copies and partially sorts a range of elements The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (funzione di modello)
stable_sort	Ordina un intervallo di elementi, mantenendo ordine tra elementi uguali Original: sorts a range of elements while preserving order between equal elements The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (funzione di modello)
sort	ordina una serie in ordine crescente Original: sorts a range into ascending order The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (funzione di modello)