All Permutations Of An Array In C++
By Anurag TiwariIn this tutorial, we shall learn to compute all permutations of an array in C++. Here we shall be using STL’s next_permutation function. The std::next_permutation is used to rearrange the elements in the range [first, last) into the next lexicographically greater permutation.
A permutation is defined as each one of the possible arrangements that can be made in factorial N ways.
The permutation is ordered lexicographically to each other. Its syntax is:
bool next_permutation (BidirectionalIterator first,
BidirectionalIterator last);Permutations Of An Array
The display function takes two arguments first one is an array and the next is its size. Similarly, the Find_Permtations function takes an array and next is its size. We have also used the std::sort which will sort the array from index a to index a+n that is from index 0 to the last index of the array. Sorting is done to get the numbers in lexicographical order starting from the first number.
#include <bits/stdc++.h>
typedef long long ll; // Macro for long long
using namespace std;
void display(ll* , ll) ; // Function for displaying the array
void Find_Permutations(ll* , ll ) ; // Function to find the permutations of array
int main()
{
ll a[] = { 1, 2, 3, 4 };
ll n = sizeof(a) / sizeof(a[0]);
Find_Permutations(a, n);
return 0;
}
void display(ll a[], ll n)
{
for (ll i = 0; i < n; i++) {
cout << a[i] << " ";
}
cout << endl;
} void Find_Permutations(ll a[], ll 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));
}It will produce the output:
Possible permutations are: 1 2 3 4 1 2 4 3 1 3 2 4 1 3 4 2 1 4 2 3 1 4 3 2 2 1 3 4 2 1 4 3 2 3 1 4 2 3 4 1 2 4 1 3 2 4 3 1 3 1 2 4 3 1 4 2 3 2 1 4 3 2 4 1 3 4 1 2 3 4 2 1 4 1 2 3 4 1 3 2 4 2 1 3 4 2 3 1 4 3 1 2 4 3 2 1
You may also like to learn:
Leave a Reply