ChiPy Algorithms SIGDescription
There are N rooms and you start in room 0. Each room has a distinct number in 0, 1, 2, ..., N-1, and each room may have some keys to access the next room.
Formally, each room i has a list of keys rooms[i], and each key rooms[i][j] is an integer in [0, 1, ..., N-1] where N = rooms.length. A key rooms[i][j] = v opens the room with number v.
Initially, all the rooms start locked (except for room 0). You can walk back and forth between rooms freely.
Return true if and only if you can enter every room.
Solution
class Solution:
def canVisitAllRooms(self, rooms):
if len(rooms) <= 1: #guard for short or empty list
return True
key_inventory = set([0]) # append only
rooms_visited = set() #append
while key_inventory - rooms_visited: # We have keys to rooms we have not seen
chosen_room = (key_inventory - rooms_visited).pop() #choose the room
keys = set(rooms[chosen_room]) # visit chosen room, get keys
key_inventory |= keys # add keys found in room to inventory
rooms_visited.add(chosen_room) # room has been visited
if key_inventory >= set(range(len(rooms))): # Stop once we have a key for each room
return True
return False # We have no keys to rooms we have not seen, and we didnt have a key for each room
Solution: Recursive
class Solution:
def __init__(self):
self.visited = set()
self.number_of_rooms = 0
def dfs(self, rms, rm):
if rm not in self.visited:
print(rm)
self.visited.add(rm)
for room_key in rms[rm]:
if room_key < self.number_of_rooms:
self.dfs(rms, room_key)
def canVisitAllRooms(self, rooms) -> bool:
if rooms:
self.number_of_rooms = len(rooms)
self.dfs(rooms, 0)
if len(self.visited) != self.number_of_rooms:
return False
else:
return True
else:
print("No Rooms to Enter")
return False