841. Keys and Rooms

leetcode841.swift

class Solution {
    func canVisitAllRooms(_ rooms: [[Int]]) -> Bool {
        
        var visited = Set<Int>()
        
        var queue = [0]
        
        while !queue.isEmpty {
            var nextQueue = [Int]()
            
            for room in queue where !visited.contains(room) {
                nextQueue.append(contentsOf: rooms[room])
                visited.insert(room)
            }
        
            queue = nextQueue
        }
        
        return visited.count == rooms.count
    }
}