std::random_shuffle, std::shuffle

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C++
 
演算法庫
功能
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Functions
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修改序列操作
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Non-modifying sequence operations
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all_of
any_of
none_of		（C++11）
（C++11）
（C++11）
for_each
count
count_if
mismatch
equal
修改序列操作
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Modifying sequence operations
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分區操作
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Partitioning operations
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is_partitioned（C++11）
partition
partition_copy（C++11）
排序操作（排序的區間）
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Sorting operations (on sorted ranges)
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is_sorted（C++11）
is_sorted_until（C++11）
sort
二進制搜索操作（排序的區間）
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Binary search operations (on sorted ranges)
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設置操作（排序的區間）
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Set operations (on sorted ranges)
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堆的操作
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Heap operations
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最小/最大操作
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Minimum/maximum operations
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數字操作
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Numeric operations
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C庫
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C library
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Defined in header <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) （至 C++11）



（C++11 起）
template< class RandomIt, class URNG >
void shuffle( RandomIt first, RandomIt last, URNG&& g );
 (3) （C++11 起）
在給定的範圍內進行重新排序元素[first, last)等，這些元素的每一個可能的排列具有相等概率的外觀.
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)
隨機數生成器是實現定義的，但經常使用的功能std::rand.
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The random number generator is implementation-defined, but the function std::rand is often used.
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2)
隨機數生成器的功能是對象r.
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The random number generator is the function object r.
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3)
隨機數生成器的功能是對象g.
Original:
The random number generator is the function object g.
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目錄

[编辑] 參數

first, last -
範圍內隨機洗牌的元素
Original:
the range of elements to shuffle randomly
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r -
函數對象作為iterator_traits<RandomIt>::difference_type如果調用返回一個隨機選擇的類型的值轉換為r(n)在區間[0，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 -
函數對象返回一個隨機選擇的值的類型URNG::result_type在區間[g.min（），栽培大豆（）]如果調用為g()（例如任何從<random>的均勻分布的隨機數發生器）
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.

[编辑] 返回值

（無）
Original:
(none)
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[编辑] 複雜性

線性first和last之間的距離
Original:
linear in the distance between first and last
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[编辑] 可能的實現

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))]);
    }
}

[编辑] 為例

下面的代碼隨機打亂整數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";
}


可能的輸出
Original:
Possible output:
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8 6 10 4 2 3 7 1 9 5

[编辑] 另請參閱

 generates the next greater lexicographic permutation of a range of elements
（函數模板） [edit]
generates the next smaller lexicographic permutation of a range of elements
（函數模板） [edit]
来自“http://zh.cppreference.com/mwiki/index.php?title=cpp/algorithm/random_shuffle&oldid=27823”