Unlock Rooms

You are given a two-dimensional list of integers rooms. Each index i in rooms represents a room and rooms[i] represents different keys to unlock other rooms.

You are currently in an unlocked room 0 and every other room is locked. Given you can move freely between unlocked rooms, return whether you can unlock every room.

Constraints

• n, m ≤ 250 where n and m are the number of rows and columns in rooms.

https://binarysearch.com/problems/Unlock-Rooms

Examples

Example 1

Input

• rooms = [[1, 3], [2], [0], []]

Output

• answer = True

Explanation

We start off at room 0 and can go to room 1 with its key. From room 1 we can go to room 2. Then, we can go back to room 0 and go to room 3.

Solution