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std::random_shuffle, std::shuffle - cppreference.com
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std::random_shuffle, std::shuffle

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Biblioteca de algoritmos
Polticas de ejecucin (C++17)
Operaciones de secuencia no modificantes
(C++11)(C++11)(C++11)
(C++17)
Operaciones de secuencia modificantes
Operaciones en almacenamiento no inicializado
Operaciones de particin
Operaciones de ordenacin
(C++11)
Operaciones de bsqueda binaria
Operaciones de conjuntos (en rangos ordenados)
Operaciones de pila
(C++11)
Operaciones mnimo/mximo
(C++11)
(C++17)
Permutaciones
Operaciones numricas
Bibliotecas C
 
Definido en el archivo de encabezado <algorithm>
template< class RandomIt >
void random_shuffle( RandomIt first, RandomIt last );
(1)
template< class RandomIt, class RandomFunc >
void random_shuffle( RandomIt first, RandomIt last, RandomFunc& r );

template< class RandomIt, class RandomFunc >
void random_shuffle( RandomIt first, RandomIt last, RandomFunc&& r );
(2) (hasta C++11)



(desde C++11)
template< class RandomIt, class URNG >
void shuffle( RandomIt first, RandomIt last, URNG&& g );
(3) (desde C++11)
Reordena los elementos en el rango dado [first, last) tales que cada permutacin posible de estos elementos tiene la misma probabilidad de aparicin .
Original:
Reorders the elements in the given range [first, last) such that each possible permutation of those elements has equal probability of appearance.
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1)
El generador de nmeros aleatorios es definido por la implementacin, pero el std::rand funcin se utiliza a menudo .
Original:
The random number generator is implementation-defined, but the function std::rand is often used.
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2)
El generador de nmeros aleatorios es el objeto de la funcin r .
Original:
The random number generator is the function object r.
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3)
El generador de nmeros aleatorios es el objeto de la funcin g .
Original:
The random number generator is the function object g.
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Parmetros

first, last -
la gama de elementos para barajar al azar
Original:
the range of elements to shuffle randomly
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r -
objeto de funcin que devuelve un valor escogido de forma aleatoria del tipo convertible a iterator_traits<RandomIt>::difference_type en el intervalo [0, n) si se invoca como r(n)
Original:
function object returning a randomly chosen value of type convertible to iterator_traits<RandomIt>::difference_type in the interval [0,n) if invoked as r(n)
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g -
objeto de funcin que devuelve un valor escogido de forma aleatoria de URNG::result_type tipo en el intervalo [g.min (), g.max ()] si invoca como g() (por ejemplo, cualquiera de los generadores de nmeros aleatorios uniformes de <random>)
Original:
function object returning a randomly chosen value of type URNG::result_type in the interval [g.min(), g.max()] if invoked as g() (e.g. any of the uniform random number generators from <random>)
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Requisitos de tipo
-
RandomIt debe reunir los requerimientos de ValueSwappable y RandomAccessIterator.
-
URNG debe reunir los requerimientos de UniformRandomNumberGenerator.

Valor de retorno

(Ninguno)
Original:
(none)
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Complejidad

lineal en la distancia entre first y last
Original:
linear in the distance between first and last
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Posible implementacin

Primera versin
template<class RandomIt, class RandomFunc>
void random_shuffle(RandomIt first, RandomIt last, RandomFunc&& r)
{
    typename std::iterator_traits<RandomIt>::difference_type i, n;
    n = last - first;
    for (i = n-1; i > 0; --i) {
        using std::swap;
        swap(first[i], first[r(i+1)]);
    }
}
Segunda versin
template<class RandomIt, class UniformRandomNumberGenerator>
void shuffle(RandomIt first, RandomIt last, 
             UniformRandomNumberGenerator&& g)
{
    typedef typename std::iterator_traits<RandomIt>::difference_type diff_t;
    typedef typename std::make_unsigned<diff_t>::type udiff_t;
    typedef typename std::uniform_int_distribution<udiff_t> distr_t;
    typedef typename distr_t::param_type param_t;

    distr_t D;
    diff_t n = last - first;
    for (diff_t i = n-1; i > 0; --i) {
        using std::swap;
        swap(first[i], first[D(g, param_t(0, i))]);
    }
}

Ejemplo

El cdigo siguiente cambia aleatoriamente los nmeros enteros 1 .. 10:
Original:
The following code randomly shuffles the integers 1..10:
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#include <random>
#include <algorithm>
#include <iterator>
#include <iostream>

int main()
{
    std::vector<int> v = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

    std::random_device rd;
    std::mt19937 g(rd());

    std::shuffle(v.begin(), v.end(), g);

    copy(v.begin(), v.end(), std::ostream_iterator<int>(std::cout, " "));
    std::cout << "\n";
}


Salida posible:
Original:
Possible output:
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8 6 10 4 2 3 7 1 9 5

Ver tambin

Genera la siguiente permutacin lexicogrfica mayor de un rango de elementos.
(plantilla de funcin) [editar]
genera la siguiente permutacin lexicogrfica menor de un rango de elementos.
(plantilla de funcin) [editar]

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