841. Keys and Rooms
DFS, BFS, Graph, AMateList ·Problem Statement
link: LeetCode.cn LeetCode 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:
Input: rooms = [[1],[2],[3],[]]
Output: true
Input: rooms = [[1,3],[3,0,1],[2],[0]]
Output: false
Solution Approach
Algorithm
Implement
class Solution: def canVisitAllRooms(self, rooms: List[List[int]]) -> bool:
# map {room: keys}
# enter = [] track the room can enter
# visited set of room number
# if enter is empty: check len(visited) == rooms
enter = deque([0])
mapR = defaultdict(list)
for r in range(len(rooms)):
mapR[r] = rooms[r]
visited = {0}
while enter:
cur = enter.popleft()
keys = mapR[cur]
for k in keys:
if not k in visited:
enter.append(k)
visited.add(k)
return len(visited) == len(rooms)