Problem URL: Reachable nodes with restrictions

We will create an adjacency list from the edges list. Then we convert our restricted list to a set for constant lookup. Then we perform a BFS to visit all the nodes, if the node is already been visited or in the restricted set, we return from that node. When our traversal from node 0 is done, we count our visited set and return.

class Solution:
    def reachableNodes(self, n: int, edges: List[List[int]], restricted: List[int]) -> int:
        graph = self.createGraph(edges)

        restricted = set(restricted)
        visited = set()
        q = collections.deque([0])

        while q:
            node = q.pop()
            visited.add(node)
            for neighbor in graph[node]:
                if neighbor not in restricted and neighbor not in visited:
                    q.appendleft(neighbor)

        return len(visited)

    def createGraph(self, edges):
        graph = collections.defaultdict(list)
        for n1, n2 in edges:
            graph[n1].append(n2)
            graph[n2].append(n1)
        return graph

Time Complexity: O(ev), e is the number of edges and v is the number of nodes
Space Complexity: O(v), v is the number of nodes