Package g0801_0900.s0841_keys_and_rooms

Class Solution

  • public class Solution
extends Object
    841 - Keys and Rooms.

    Medium

    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.

    • Constructor Detail

      • Solution

        public Solution()

    • Method Detail

      • canVisitAllRooms

        public boolean canVisitAllRooms​(List<List<Integer>> rooms)