Sorting Array of 0’s and 1’s

You are given an Array of N size. It contains 0 and 1 only. You have to arrange all 0s before all 1s (In the program you can’t travel more than once. Minimum complexity desired).

Idea : Move a pointer left, from the front, until it encounters a 1
Move a pointer right, from the end, until it encounters a 0
Swap the elements at the two pointers (if they haven’t crossed)
Repeat this for entire array – this is inplace and single pass.

Code :

public class swap01
{
public static void main(String arg[])
{
int[] a = {0,1,1,0,0,1,1,1,0};
int l =0;
int r= a.length-1;
while(l {
if(a[l] == 0)
{
l++;
}
else if(a[r] == 1)
{
r–;
}
else {
swap(a,l,r);
l++;
r–;
}
}
for(int i=0;i System.out.print(a[i] + ",");
}
private static void swap(int[] a, int l, int r)
{
int tmp = a[l];
a[l] = a[r];
a[r]=tmp;
}
}