Code Fragment: height1

int height1(const Tree& T) {
   int h = 0;
   PositionIterator nodes = T.positions();
   while (nodes.hasNext()) {
     Position v = nodes.next();
     if (T.isExternal(v))				// v is a leaf?
       h = max(h, depth(T, v));				// max depth among leaves
   }
   return h;
 }