Given a Category lambda, left node, right node., I want to know the parent node.
"""
node* get_parent(node* N)
{
//define parent of nullptr to be nullptr
if (!N)
return nullptr;
while (true)
{
if (N->left)
{
//N->left is either the previous sibling or the parent
if (N->left->child == N) //N->left is the parent
return N->left;
else //N->left is the previous sibling
N = N->left;
}
else //a node with left==nullptr is the root, so its parent is nullptr
{
return nullptr;
}
}
}
"""
