Reverse Dutch Flag problem

Given an array a1 a2 a3 a4.. b1 b2 b3... convert it to a1 b1 a2 b2 a3 b3 ...

 public static void main(String[] args) {
  int a[]={0,0,0,0,1,1,1,1};
  reverseDutch(a,0,a.length-1);
  for(int b : a)
    System.out.print(b);;
  
 }
 
 public static void reverseDutch(int a[],int low,int high){
  
  if(low==high) return;
  
  int centre=(low+high)/2;
  int start= 1 + (low+centre)/2;
  //swap elements ard centre
  // 00001111 => 00110011 => 01010101
  for(int k=1,i=start;i<=centre;i++,k++){
   int temp=a[i];
   a[i]=a[centre+k];
   a[centre+k]=temp;
   
  }
  
  reverseDutch(a,low,centre);
  reverseDutch(a,centre+1,high);
  
 }

O(n lgn)