All permutations of an array using STL in C++

Given an array, the task is to print or display all the permutations of this array using STL in C++.

Examples:

Input: a[] = {1, 2, 3}
Output:
1  2  3  
1  3  2  
2  1  3  
2  3  1  
3  1  2  
3  2  1  

Input: a[] = {10, 20, 30, 40}
Output:
10  20  30  40  
10  20  40  30  
10  30  20  40  
10  30  40  20  
10  40  20  30  
10  40  30  20  
20  10  30  40  
20  10  40  30  
20  30  10  40  
20  30  40  10  
20  40  10  30  
20  40  30  10  
30  10  20  40  
30  10  40  20  
30  20  10  40  
30  20  40  10  
30  40  10  20  
30  40  20  10  
40  10  20  30  
40  10  30  20  
40  20  10  30  
40  20  30  10  
40  30  10  20  
40  30  20  10

Approach: The next possible permutation of the array can be found using next_permutation() function provided in STL.

Syntax:

bool next_permutation (BidirectionalIterator first,
                       BidirectionalIterator last);

Below is the implementation of the above Approach:

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// C++ program to display all permutations
// of an array using STL in C++
  
#include <bits/stdc++.h>
using namespace std;
  
// Function to display the array
void display(int a[], int n)
{
    for (int i = 0; i < n; i++) {
        cout << a[i] << "  ";
    }
    cout << endl;
}
  
// Function to find the permutations
void findPermutations(int a[], int n)
{
  
    // Sort the given array
    sort(a, a + n);
  
    // Find all possible permutations
    cout << "Possible permutations are:\n";
    do {
        display(a, n);
    } while (next_permutation(a, a + n));
}
  
// Driver code
int main()
{
  
    int a[] = { 10, 20, 30, 40 };
  
    int n = sizeof(a) / sizeof(a[0]);
  
    findPermutations(a, n);
  
    return 0;
}

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Output:

Possible permutations are:
10  20  30  40  
10  20  40  30  
10  30  20  40  
10  30  40  20  
10  40  20  30  
10  40  30  20  
20  10  30  40  
20  10  40  30  
20  30  10  40  
20  30  40  10  
20  40  10  30  
20  40  30  10  
30  10  20  40  
30  10  40  20  
30  20  10  40  
30  20  40  10  
30  40  10  20  
30  40  20  10  
40  10  20  30  
40  10  30  20  
40  20  10  30  
40  20  30  10  
40  30  10  20  
40  30  20  10


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