## DEV Community

Abhishek Chaudhary

Posted on

# Keys and Rooms

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.

Constraints:

• `n == rooms.length`
• `2 <= n <= 1000`
• `0 <= rooms[i].length <= 1000`
• `1 <= sum(rooms[i].length) <= 3000`
• `0 <= rooms[i][j] < n`
• All the values of `rooms[i]` are unique.

SOLUTION:

``````class Solution:
def canVisitAllRooms(self, rooms: List[List[int]]) -> bool:
beg = 0
paths = [beg]
visited = {beg}
while len(paths) > 0:
curr = paths.pop()
for j in rooms[curr]:
if j not in visited: