1192-critical-connections

from collections import deque

class Solution:
    def bfsNodes(n: int, adj_list: List[List[int]]) -> int:
        if len(adj_list[0]) == 0:
            return 0
        visited = set()
        q = deque([0])
        while q:
            curr_node = q.pop()
            visited.add(curr_node)
            for conn_node in adj_list[curr_node]:
                if conn_node not in visited:
                    q.append(conn_node)
        return len(visited)

    def criticalConnections(self, n: int, connections: List[List[int]]) -> List[List[int]]:
        critical_conns = []
        # 1. remove one connection
        for removed_conn in connections:
            # 2. create adj list
            adj_list = [[] for _ in range(n)]
            for conn in connections:
                if conn != removed_conn:
                    adj_list[conn[0]].append(conn[1])
                    adj_list[conn[1]].append(conn[0])
            # 3. run bfs, calculate number of distinct visited nodes;
            #    if less than n, this is a critical connection
            visited_number = self.bfsNodes(adj_list)
            if visited_number < n:
                critical_conns.append(removed_conn)
        return critical_conns