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Showing content from https://cplusplus.com/reference/algorithm/shuffle/ below:

function template

<algorithm>

template <class RandomAccessIterator, class URNG>  void shuffle (RandomAccessIterator first, RandomAccessIterator last, URNG&& g);

Randomly rearrange elements in range using generator

The function swaps the value of each element with that of some other randomly picked element. The function determines the element picked by calling g().

This function works with standard generators as those defined in <random>. To shuffle the elements of the range without such a generator, see random_shuffle instead.

The behavior of this function template is equivalent to:

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template <class RandomAccessIterator, class URNG>
  void shuffle (RandomAccessIterator first, RandomAccessIterator last, URNG&& g)
{
  for (auto i=(last-first)-1; i>0; --i) {
    std::uniform_int_distribution<decltype(i)> d(0,i);
    swap (first[i], first[d(g)]);
  }
}

first, last

Forward iterators to the initial and final positions of the sequence to be shuffled. The range used is [first,last), which contains all the elements between first and last, including the element pointed by first but not the element pointed by last.
ForwardIterator shall point to a type for which swap is defined and swaps the value of its arguments.

g

A uniform random number generator, used as the source of randomness.
URNG shall be a uniform random number generator, such as one of the standard generator classes (see <random> for more information).

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// shuffle algorithm example
#include <iostream>     // std::cout
#include <algorithm>    // std::shuffle
#include <array>        // std::array
#include <random>       // std::default_random_engine
#include <chrono>       // std::chrono::system_clock

int main () {
  std::array<int,5> foo {1,2,3,4,5};

  // obtain a time-based seed:
  unsigned seed = std::chrono::system_clock::now().time_since_epoch().count();

  shuffle (foo.begin(), foo.end(), std::default_random_engine(seed));

  std::cout << "shuffled elements:";
  for (int& x: foo) std::cout << ' ' << x;
  std::cout << '\n';

  return 0;
}

shuffled elements: 3 1 4 2 5

random_shuffle

Randomly rearrange elements in range (function template)

default_random_engine

Default random engine (class)

swap

Exchange values of two objects (function template)

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