keys-and-rooms_841.py

# There are n rooms labeled from 0 to n - 1 and all the rooms are locked except for room 0. Your goal is to visit all the rooms. However, you cannot enter a locked room without having its key.

# When you visit a room, you may find a set of distinct keys in it. Each key has a number on it, denoting which room it unlocks, and you can take all of them with you to unlock the other rooms.

# Given an array rooms where rooms[i] is the set of keys that you can obtain if you visited room i, return true if you can visit all the rooms, or false otherwise.


# Example 1:

# Input: rooms = [[1],[2],[3],[]]
# Output: true
# Explanation:
# We visit room 0 and pick up key 1.
# We then visit room 1 and pick up key 2.
# We then visit room 2 and pick up key 3.
# We then visit room 3.
# Since we were able to visit every room, we return true.
# Example 2:

# Input: rooms = [[1,3],[3,0,1],[2],[0]]
# Output: false
# Explanation: We can not enter room number 2 since the only key that unlocks it is in that room.

# ---------------------------------------Runtime 67 ms Beats 83.66% Memory 16.8 MB Beats 71.15%---------------------------------------

from collections import deque


# Time Complexity O(n * k)
class Solution:
    def canVisitAllRooms(self, rooms: list[list[int]]) -> bool:
        deq = deque([0])
        visited = set()

        while deq:
            ind = deq.popleft()
            if ind not in visited:
                deq.extend(rooms[ind])
                visited.add(ind)
        return len(visited) == len(rooms)