Implement method to get possible nodes from ticket list

src/syai/game.py

@@ -38,14 +38,26 @@ class Board:
 
         return graph
 
-    def __init__(self):
-        self.ticket_graphs = {}
-
     def add_connection(self, ticket: str, departure: str, destination: str, oneway: bool = False) -> None:
         self.ticket_graphs.setdefault(ticket, {}).setdefault(departure, set()).add(destination)
         if not oneway:
             self.ticket_graphs.setdefault(ticket, {}).setdefault(destination, set()).add(departure)
 
+    def get_possible_nodes(self, last: str, tickets: list[str]) -> list[str]:
+        possible = set((last,))
+        for ticket in tickets:
+            graph = self.full_graph if ticket == "*" else self.ticket_graphs[ticket]
+
+            new_possible = set()
+            for node in possible:
+                new_possible.update(graph[node])
+            possible = new_possible
+
+        return possible
+
+    def __init__(self):
+        self.ticket_graphs = {}
+
     @classmethod
     def from_dot(cls, filename: str) -> "Board":
         board = cls()