A little help please

void reverseHalves(int a[], int size)
{
    int i, t;

      if((size%2) != 0)  Size ODD
      {
        for(i=0;i<=((size/2)-1);i++)
        {
            t = a[i];
            a[i] = a[(size/2)+i+1];
            a[(size/2)+i+1] = t;
        }
      }

      if((size%2) == 0)  Size EVEN
      {
        for(i=0;i<=((size/2)-1);i++)
         {
              t = a[i];
              a[i] = a[(size/2)+i];
              a[(size/2)+i] = t;
          }
      }

    return;
}


This function swaps the halves of an array.

e.g.

1
2
3
4

comes out as:

3
4
1
2

I handed it in to my professor and he said he wants me to do it over using only one loop. The reason I used two loops in the first place because the program would crash when based on whether or not an odd/even amount of elements were present for the array. He said I could used a nested for loop, but I haven't been able to figure out how to create it.

reverse = lambda a: a[len(a) >> 1:] + a[:len(a) >>1]