Advent of Code day 6

orbit.py

class Node:
    def __init__(self, value):
        self.value = value
        self.adjacent = []

    def is_santa(self):
        return self.value == "SAN"

    def is_you(self):
        return self.value == "YOU"

    def add_adjacent(self, child):
        self.adjacent.append(child)


class Graph:
    def __init__(self, root):
        self.root = root
        self.distance = 0

    def count_orbits(self):
        visited = set()

        def recurse(node, counter):
            visited.add(node)

            adjacent = [n for n in node.adjacent if n not in visited]
            if not adjacent:
                return None

            for n in adjacent:
                if n.is_santa():
                    return counter

            results = [recurse(child, counter + 1) for child in adjacent]
            results = [result for result in results if result is not None]
            if results:
                return min(results)

            return None

        return recurse(self.root, 0)


def parse_graph(input_filename):
    node_map = {}
    with open(input_filename) as stream:
        line = stream.readline()
        while line:
            node_tuple = line.strip().split(')')

            if node_map.get(node_tuple[0]) is None:
                node_map[node_tuple[0]] = Node(node_tuple[0])
            parent = node_map[node_tuple[0]]

            if node_map.get(node_tuple[1]) is None:
                node_map[node_tuple[1]] = Node(node_tuple[1])
            child = node_map[node_tuple[1]]

            parent.add_adjacent(child)
            child.add_adjacent(parent)

            line = stream.readline()

    for node in node_map.values():
        if node.is_you():
            return Graph(node)

assert parse_graph("input_test2").count_orbits() == 5
print("santa_distance ok")
print(parse_graph("input").count_orbits())