Arrange 0's & 1's in a array

Question

This is one of an interview question which I had recently. I would like to know others perception of approach for this problem.

Question:

Yo

Answer 1

#include
//#include

int main()
{
  int i,a[20]={0};
  int *ptr1,*ptr2;
  //clrscr();
  //a[2]=a[4]=a[6]=a[8]=a[16]=1;
  a[19]=a[18]=1;

  for(i=0;i<20;i++)
    printf("%d",a[i]);

  printf("\n\nafter");

  ptr1=ptr2=a;
  for(i=0;i<20;i++)
  {
    if(*ptr1==0&&*ptr2==1)
    {
      int temp=*ptr1;*ptr1=*ptr2;*ptr2=temp;
      ptr1++;ptr2++;
    }
    else if(*ptr1==1&&*ptr2==0)
    {
      ptr1++;ptr2++;
    }
    else if(*ptr1==0&&*ptr2==0)
    {
      ptr2++;
    }
    else
    {
      if(ptr1