Separate even and odd | if order doesn't matter

Question - 

Given an array A[], write a function that segregates even and odd numbers. The functions should put all even numbers first, and then odd numbers.

Note - ordre doesn't matter.

Example - 

Input :arr[] = {1, 2, 3, 4, 5, 6}

Output : {2, 4, 6, 1, 3, 5}

Approach -

we start from starting point , if we got any odd number then we swap this by ending element and decrease ending index else increase starting index.

Implementation - 

#include<iostream>

using namespace std;

void separate(int arr[],int n)

{

    int left=0,right=n-1;

    while(left<right){

        if(arr[left]%2!=0){

            swap(arr[left],arr[right]);

            right--;

        }

        else

        left++;

    }

}

int main()

{

    int n;

    cout<<"Enter the number of the elements : ";cin>>n;

    int arr[n];

    cout<<"Enter elements : "<<endl;

    for(int i=0;i<n;i++)

        cin>>arr[i];

    separate(arr,n);

    for(int i=0;i<n;i++)

        cout<<arr[i]<<" ";

    cout<<endl;

    return 0;

}

Time complexity - O(n)