public int[] sortCows (int[] cows) {
        // write code here
        int l=0;
        int r=cows.length-1;
        while(l<r){
            if(cows[l]==1){
                swap(cows,l,r);
            r--;
            }
            else l++; 
        }
        return cows;
    }
    private void swap(int[] cows,int l,int r){
        int temp=cows[l];
        cows[l]=cows[r];
        cows[r]=temp;
    }