# How to shuffle a std::vector in C++

C++Server Side ProgrammingProgramming

A vector shuffle can be done in the Fisher-Yates shuffle algorithm.

In this algorithm, a linear scan of a vector is done and then swap each element with a random element among all the remaining element, including the element itself.

## Algorithm

Begin
Declare a function show().
Pass a constructor of a vector as a parameter within show() function.
for (auto const& i: input)
Print the value of variable i.
Declare v of vector type.
Initialize some values into v vector in array pattern.
Declare a variable size of the integer datatype.
Call size() function to get the size of the vector.
Initialize size = v.size().
for (int i = 0; i < size - 1; i++)
int j = i + rand() % (size - i).
call swap() function to swap the values of v[i] and v[j].
print “Elements after getting shuffled”.
Call show() function to display the suffled value of v vector.
End.

## Example Code

Live Demo

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
void show(vector<int> const &input) {
for (auto const& i: input) {
std::cout << i << " ";
}
}
int main() {
vector<int> v = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
int size = v.size();
for (int i = 0; i < size - 1; i++) {
int j = i + rand() % (size - i);
swap(v[i], v[j]);
}
cout<<"Elements after getting shuffled"<<endl;
show(v);
return 0;
}

## Output

Elements after getting shuffled
2 8 5 3 1 9 4 7 6
Published on 02-Apr-2019 12:46:24
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