same for tree2
Node * temp2 = s2 . top ( ) ; s2 . pop ( ) ; while ( temp2 != NULL && ! isLeaf ( temp2 ) ) { if ( temp2 -> right ) s2 . push ( temp2 -> right ) ; if ( temp2 -> left ) s2 . push ( temp2 -> left ) ; temp2 = s2 . top ( ) ; s2 . pop ( ) ; }