The tree itself will need destructors to clean up allocations, and that's what's problematic here: if the tree is destroyed top down, the destructor of the chil

The tree itself will need destructors to clean up allocations, and that's what's problematic here: if the tree is destroyed top down, the destructor of the children may access the parent which has already been invalidated, and similarly destroying bottom up risks the destructor of the parent accessing the children.