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std::nth_element

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< cpp‎ | algorithm

 
 
Biblioteca de algoritmos
Políticas de ejecución (C++17)
Operaciones no modificadoras de secuencia
(C++11)(C++11)(C++11)
(C++17)
Operaciones modificadoras de secuencia
Operaciones en almacenamiento no inicializado
Operaciones de partición
Operaciones de ordenación
(C++11)
nth_element

Operaciones de búsqueda binaria
Operaciones de set (en rangos ordenados)
Operaciones de pila
(C++11)
Operaciones minimo/maximo
(C++11)
(C++17)
Permutaciones
Operaciones numéricas
Bibliotecas C
 
Definido en la cabecera <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)
Parcialmente el tipo [first, last) rango en orden ascendente de manera que todos los elementos en el intervalo [first, nth) son' menos que aquellos en el rango [nth, last). La primera versión utiliza operator< para comparar los elementos, la segunda versión utiliza la comparación comp función dada. El elemento colocado en la posición nth es exactamente el elemento que se producirían en esta posición si el rango se solucionó completamente .
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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Contenido

[editar] Parámetros

first, last -
iteradores de acceso aleatorio que definen el tipo gama
Original:
random access iterators defining the range sort
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nth -
iterador de acceso aleatorio que determina el punto de partición tipo
Original:
random access iterator defining the sort partition point
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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. ​

Requerimientos de tipo
-
RandomIt debe reunir los requerimientos de ValueSwappable y RandomAccessIterator.
-
The type of dereferenced RandomIt must meet the requirements of MoveAssignable and MoveConstructible.

[editar] Valor de retorno

(Ninguno)
Original:
(none)
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[editar] Complejidad

Lineal en std::distance(first, last) en promedio .
Original:
Linear in std::distance(first, last) on average.
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[editar] Ejemplo

#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';
}

Salida:

The median is 5
The second largest element is 7

[editar] Ver también

copias y clasifica parcialmente una serie de elementos
Original:
copies and partially sorts a range of elements
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(plantilla de función) [editar]
Ordena un intervalo de elementos, mientras que la preservación del orden entre los elementos iguales
Original:
sorts a range of elements while preserving order between equal elements
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(plantilla de función) [editar]
Ordena un intervalo en orden ascendente
Original:
sorts a range into ascending order
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(plantilla de función) [editar]