Fullstack Developer

You have been given a board where there are '2' rows and 'N' columns. You have an infinite supply of 2x1 tiles, and you can place a tile in the following ways:

1. Horizontally as 1x2 tile
2. Vertically as 2x1 tile

Count the number of ways to tile the given board using the available tiles.

Note :

The number of ways might be large so output your answer modulo 10^9 + 7.

Here an example of tile and board for 'N' = 4 :

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.