[LeetCode] Medium - 841 Keys and Rooms

▶841 - Keys and Rooms

▶문제

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.

 

▶예제

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.

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.

 

▶풀이

dfs를 이용해서 탐색으로 풀었다.

만약에 갈 수 없는 노드가 있다면 visit에 0이 남아 있을 거다.

그렇게 판단해주었다.

class Solution:
    def canVisitAllRooms(self, rooms: List[List[int]]) -> bool:
        def dfs(node):
            if visit[node] == 1:
                return 
            visit[node] = 1
            for room in rooms[node]:
                if visit[room] == 1:
                    continue
                dfs(room)

        visit = [0 for _ in range(len(rooms))]
        dfs(0)

        if 0 in visit:
            return False
        return True