Full array of question number algorithm set ---

Description of the problem
The n digital 1,2, ... n are all arranged lexicographically enumerated monkey
Input:
n
output:
. 1 2. 3
. 1. 3 2
2. 3. 1
2. 1. 3
. 3. 1 2
. 3. 1 2

#include <iostream>
#include <algorithm>
using namespace std;
int main ()
{
	int n;
    cin>>n;
    int arr[n];
	for(int i=1;i<=n;i++)
	    arr[i-1]=i;
    do{
    	for(int i=0;i<n;i++)
            cout<<arr[i]<<" ";
        cout<<endl;
    }while(next_permutation(arr,arr+n));
    return 0;
}