challenge activity

$16\mathrm{.}12\mathrm{.}2$: Show how the recursive helper function can be implemented as a member function of the Node class.

$595628\mathrm{.}3923258.$qx$3$zqy$7$

The BinaryTree class of the "A Binary Tree Implementation" subsection of the "Binary Trees" section contains a recursive helper function named height. Show how the recursive helper function can be implemented as a member function of the Node class instead. Note that doing this requires multiple checks for nullptr while the original version required only one.