SDE - 1

You have been given a binary tree of integers with N number of nodes. Your task is to check if that input tree is a BST (Binary Search Tree) or not.

A binary search tree (BST) is a binary tree data structure which has the following properties.

• The left subtree of a node contains only nodes with data less than the node’s data.
• The right subtree of a node contains only nodes with data greater than the node’s data.
• Both the left and right subtrees must also be binary search trees.

Example :

Answer :

Level 1: 

All the nodes in the left subtree of 4 (2, 1, 3) are smaller 
than 4, all the nodes in the right subtree of the 4 (5) are 
larger than 4.

Level 2 :

For node 2:
All the nodes in the left subtree of 2 (1) are smaller than 
2, all the nodes in the right subtree of the 2 (3) are larger than 2.
For node 5:
The left and right subtrees for node 5 are empty.

Level 3:

For node 1:
The left and right subtrees for node 1 are empty.
For node 3:
The left and right subtrees for node 3 are empty.

Because all the nodes follow the property of a binary search tree, the above tree is a binary search tree.

Mislabeled Jars : 
There are 3 jars, namely, A, B, C. All of them are mislabeled. Following are the labels of each of the jars:

A: Candies
B: Sweets
C: Candies and Sweets (mixed in a random proportion)

You can put your hand in a jar and pick only one eatable at a time. Tell the minimum number of eatable(s) that has/have to be picked in order to label the jars correctly.

You have been given an array/list ‘ARR’ of integers consisting of ‘N’ integers. You are also given a size ‘M’. You need to display the median of all the subarrays of size ‘M’ and it is starting from the very left of the array.

Median is the middle value in an ordered integer array/list. If the size of the array/list is even there is no middle element. So the median is the mean of two middle values in an even size array/list.

Your task is to return the median of all the subarrays whose size is ‘M’.

Example:

Let’s say you have an array/list [1,4,3,5] and ‘M’ is 3.Then the first subarray of size 3 is [1,4,3] whose median is 3.Then the second subarray of size 3 is [4,3,5] whose median is 4. Therefore the median of all the subarrays of size 3 is [3.0,4.0].

Given a binary tree, we need to install cameras on the nodes of the tree. Each camera at a node monitors its parent, itself, and its immediate children. Calculate the minimum number of cameras needed to monitor all nodes of the tree.