5.5.6 Symmetric Case

Here's the code for the symmetric case, where the deleted node was in the right subtree of its parent.

177. <Update y's balance factor after right-side AVL deletion 177> =
y->avl_balance–;
if (y->avl_balance == -1)
  break;
else if (y->avl_balance == -2) 
  {
    struct avl_node *x = y->avl_link[0];
    if (x->avl_balance == +1) 
      {
        struct avl_node *w;
        <Rotate left at x then right at y in AVL tree 156>
        pa[k - 1]->avl_link[da[k - 1]] = w;
      } 
    else 
      {
        y->avl_link[0] = x->avl_link[1];
        x->avl_link[1] = y;
        pa[k - 1]->avl_link[da[k - 1]] = x;
        if (x->avl_balance == 0) 
          {
            x->avl_balance = +1;
            y->avl_balance = -1;
            break;
          }
        else 
          x->avl_balance = y->avl_balance = 0;
      }
  }

This code is included in 171.