Find All Children Of Top Parent In Python

I have a list of parent-child relations where the structure isn't a true tree. Some parents can have many children and also some children can have more than one parent. import pan

Solution 1:

As you said, it's not really a tree, but more like a directed acyclic graph, so you can't map each child to just one parent; it'd have to be a list of parents. Also, given your use case, I'd suggest mapping parents to their lists of children instead.

relations = [[123,234],[234,345],[123,235],[123,236],[124,236],[236,346]]

children = {}
for p, c in relations:
    children.setdefault(p, []).append(c)
roots = set(children) - set(c for cc in children.values() for c in cc)

You can then use a recursive function similar to the one you already have to get all the children to a given root node (or any parent node). The root itself is not in the list, but can easily be added.

def all_children(p):
    if p not in children:
        return set()
    return set(children[p] + [b for a in children[p] for b in all_children(a)])

print({p: all_children(p) for p in roots})
# {123: {234, 235, 236, 345, 346}, 124: {346, 236}}