Separate 0s and 1s in an array

Question - 

Given an array of 0s and 1s in random order. separate 0s on the left side and 1s on the right side of the array.

Example -

Input : arr[] = {1, 0, 1, 1, 1, 1, 0, 0, 0, 1}

Output : {0, 0, 0, 0, 1, 1, 1, 1, 1, 1}

Approach - 

We count the number of zeros in the array. and then we reinitilize the array with 0s and 1s.

Implementation - 

#include<iostream>

using namespace std;

void separate(int arr[],int n)

{

    int zeros=0;

    for(int i=0;i<n;i++){

        if(arr[i]==0)

            zeros++;

    }

    for(int i=0;i<zeros;i++)

        arr[i]=0;

    for(int i=zeros;i<n;i++)

        arr[i]=1;

}

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)