Question 43 of 75 - LeetCode Weekly Challenge

LeetCode Challenge #841. Keys and Rooms

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
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.



  • 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.
Video Solution
C++ Solution
					class Solution {
    void dfs(vector<vector<int>>& rooms,vector<bool>& visited, int currRoom)
        for(auto next:rooms[currRoom])
    bool canVisitAllRooms(vector<vector<int>>& rooms) {
        int n=rooms.size();
        vector<bool> visited(n,false);

        for(auto eachRoom:visited)
            if(!eachRoom)return false;
        return true;

Happy Coding with edSlash