SDE - 1

You are given some information about the rooms of a military camp. The rooms are numbered from 0 to 'N-1'. Each room contains keys to some other rooms. You can visit a room only if you have a key to that room. Your task is to determine whether each room can be visited or not.

Note:

1. Room 0 is the only room that is initially unlocked and doesn’t require any key to enter.

2. Any other room can be visited only if you have the key to that room.

3. More than one room can have keys to the same room.

4. You are allowed to visit rooms in any order.

5. You can visit any room multiple times.

You are given a singly linked list that may or may not contain a cycle. You are supposed to return the node where the cycle begins, if a cycle exists, else return 'NULL'.

A cycle occurs when a node's next pointer returns to a previous node in the list.

Example:

In the given linked list, there is a cycle starting at position 0, hence we return 0.

Suppose, your company has taken over another company. The product has a huge code base. Your manager has assigned you a task to find the dead code and eliminate it.

You want to design a game, 2D game. There are many objects in on the screen. You need to find whether these objects are overlapped or not. Size of the screen is given.
For simplicity, take the shape of the 2 objects be rectangle.
 

You have a binary tree of 'N' unique nodes and a Start node from where the tree will start to burn. Given that the Start node will always exist in the tree, your task is to print the time (in minutes) that it will take to burn the whole tree.

It is given that it takes 1 minute for the fire to travel from the burning node to its adjacent node and burn down the adjacent node.

For Example :

For the given binary tree: [1, 2, 3, -1, -1, 4, 5, -1, -1, -1, -1]
Start Node: 3

    1
   / \
  2   3
     / \
    4   5

Output: 2

Explanation :
In the zeroth minute, Node 3 will start to burn.

After one minute, Nodes (1, 4, 5) that are adjacent to 3 will burn completely.

After two minutes, the only remaining Node 2 will be burnt and there will be no nodes remaining in the binary tree. 

So, the whole tree will burn in 2 minutes.