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std::random_shuffle, std::shuffle

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C++
 
Bibliothèque d'algorithmes
Fonctions
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Functions
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Non-modification de la séquence des opérations
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Non-modifying sequence operations
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Modification de la séquence des opérations
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Modifying sequence operations
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Des opérations de partitionnement
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Partitioning operations
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Opérations de tri (sur les gammes triés)
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Sorting operations (on sorted ranges)
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is_sorted (C++11)
is_sorted_until (C++11)
sort
Opérations binaires de recherche (sur les gammes triés)
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Binary search operations (on sorted ranges)
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Définir les opérations (sur les gammes triés)
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Set operations (on sorted ranges)
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Opérations Heap
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Heap operations
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Minimum / maximum de fonctionnement
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Minimum/maximum operations
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Opérations numériques
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Numeric operations
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Bibliothèque C
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C library
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Déclaré dans l'en-tête <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) (avant C++11)



(depuis C++11)
template< class RandomIt, class URNG >
void shuffle( RandomIt first, RandomIt last, URNG&& g );
 (3) (depuis C++11)
Réordonne les éléments de la gamme proposée [first, last) de sorte que chaque permutation possible de ces éléments a une probabilité égale d'apparence .
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)
Le générateur de nombres aléatoires est définie par l'implémentation, mais le std::rand fonction est souvent utilisée .
Original:
The random number generator is implementation-defined, but the function std::rand is often used.
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2)
Le générateur de nombres aléatoires est l'objet r fonction .
Original:
The random number generator is the function object r.
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3)
Le générateur de nombres aléatoires est l'objet g fonction .
Original:
The random number generator is the function object g.
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Sommaire

[modifier] Paramètres

first, last -
la plage d'éléments à mélanger de manière aléatoire
Original:
the range of elements to shuffle randomly
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r -
objet fonction retournant une valeur choisie au hasard de type convertible en iterator_traits<RandomIt>::difference_type dans l'intervalle [0, n) si elle est invoquée comme 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 -
objet fonction retournant une valeur choisie au hasard de URNG::result_type type dans l'intervalle [g.min (), g.max ()] si elle est invoquée comme g() (par exemple, l'un des générateurs de nombres aléatoires 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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Type requirements
-
RandomIt must meet the requirements of ValueSwappable and RandomAccessIterator.
-
URNG must meet the requirements of UniformRandomNumberGenerator.

[modifier] Retourne la valeur

(Aucun)
Original:
(none)
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[modifier] Complexité

linéaire de la distance entre first et last
Original:
linear in the distance between first and last
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[modifier] Mise en œuvre possible

First version 
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)]);
    }
}
Second version 
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))]);
    }
}

[modifier] Exemple

Le code suivant modifie de façon aléatoire les entiers de 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";
}


Sortie possible:
Original:
Possible output:
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8 6 10 4 2 3 7 1 9 5

[modifier] Voir aussi
génère la plus grande lexicographique prochaine permutation d'un ensemble d'éléments
Original:
generates the next greater lexicographic permutation of a range of elements
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(fonction générique) [edit]
lexicographique génère le plus petit côté d'une permutation série d'éléments
Original:
generates the next smaller lexicographic permutation of a range of elements
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(fonction générique) [edit]
Récupérée de « https://fr.cppreference.com/mwiki/index.php?title=cpp/algorithm/random_shuffle&oldid=47543 »