SDE - 1

You have been given a sorted (lexical order) dictionary of an alien language.

Write a function that returns the order of characters as a string in the alien language. This dictionary will be given to you as an array of strings called 'dictionary', of size 'N'.

Example :

If the dictionary consists of the following words:-
["caa", "aaa", "aab"], and 'K' is 3.

Then, the order of the alphabet is -
['c', 'a', 'b']

Note:

If the language consists of four letters, the four letters should be the starting four letters of the English language. 

However, their order might differ in the alien language.

You are given a positive integer 'N'. Your task is to find the number of strings of length ‘N’ that can be formed using only the characters ‘a’, ‘b’ and ‘c’. The strings formed should be such that the number of ‘b’ and ‘c’ in the string is at most 1 and 2, respectively.

Example:

Let’s say N = 2. The strings of length 2, which satisfy the given constraints are: “aa”, “ab”, “ac”, “ba”, “bc”, “ca”, “cb”, “cc”. Hence, the output is 8.

You have been given a Binary Search Tree (BST) of integer values and 2 integers 'LOW' and 'HIGH' denoting range ['LOW', 'HIGH'].

Your task is to return the count of nodes where all the nodes under that node (or subtree rooted with that node) lie in the given range.

A binary search tree (BST) is a binary tree data structure with 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:

Consider the following binary search tree. Suppose the given range is [ 15, 32 ] so we return ‘2’ as an answer as there are two nodes whose subtree is in the given range, the nodes are 20 and 30.