Swapping largest and smallest element of an array C++

#include<iostream>
using namespace std;

int main()
{
    int n, largest, smallest;
    int b_index, s_index;
    cout<<"Enter array length: ", cin>>n;
    int arr[n];
    cout<<"\nEnter array elements:\n";
    for(int i=0; i<n; i++) {
        cin >> arr[i];
    }
    if(arr[0]>arr[1]) {
        largest=arr[0];
        b_index=0;
        smallest=arr[1];
        s_index=1;
    } else {
        largest=arr[1];
        b_index=1;
        smallest=arr[0];
        s_index=0;
    }
    for(int i=2; i<n; i++)
    {
        if(arr[i]>largest) {
            largest=arr[i];
            b_index=i;
        } else if (arr[i]<smallest) {
            smallest=arr[i];
            s_index=i;
        }
    }
    cout<<"\nArray after swapping largest and smallest element:\n";
    arr[b_index]=smallest;
    arr[s_index]=largest;
    for(int i=0; i<n; i++) {
        cout<<arr[i]<<endl;
    }
    return 0;
}