SDE - 1

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 an Encrypted String where repetitions of substrings are represented as substring followed by the count of substrings.

Example: String "aabbbcdcdcd" will be encrypted as "a2b3cd3".

You need to find the 'K'th character of Decrypted String. Decrypted String would have 1-based indexing.

Note :

Input string will always be lowercase characters without any spaces.

If the count of a substring is 1 then also it will be followed by Integer '1'.
Example: "aabcdee" will be Encrypted as "a2bcd1e2"
This means it's guaranteed that each substring is followed by some Integer.

Also, the frequency of encrypted substring can be of more than one digit. For example, in "ab12c3", ab is repeated 12 times. No leading 0 is present in the frequency of substring.

The frequency of a repeated substring can also be in parts.
Example: "aaaabbbb" can also have "a2a2b3b1" as Encrypted String.

Given an array of distinct integers, find all the pairs having positive value and negative value of a number that exists in the array. Return the pairs in any order.

Note:

The pair consists of equal absolute values, one being positive and another negative.

Return an empty array, if no such pair exists.

You are given an integer array 'arr' of size 'N' and an integer 'K'.

Your task is to find the total number of subarrays of the given array whose sum of elements is equal to k.

A subarray is defined as a contiguous block of elements in the array.

Example:

Input: ‘N’ = 4, ‘arr’ = [3, 1, 2, 4], 'K' = 6

Output: 2

Explanation: The subarrays that sum up to '6' are: [3, 1, 2], and [2, 4].