Table of Contents

## Question

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:trueExplanation: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:falseExplanation: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**.

## Python Solution

class Solution: def canVisitAllRooms(self, rooms: List[List[int]]) -> bool: dfs = [0] seen = set(dfs) while dfs: x = dfs.pop() for i in rooms[x]: if i not in seen: dfs.append(i) seen.add(i) if len(seen)==len(rooms):return True return False