Software Engineer

Given an input string 'S' and a pattern 'P', implement a regular expression matching with the support of two special characters ‘.’ (dot) and ‘*’(asterisk) where

1. ‘.’ matches to any single character.
2. ‘*’ matches to zero or more of the preceding element.

If the input string 'S' matches the pattern 'P', then return true else, return false.

Note:

1. You have to match the entire string with the pattern given.

2. Both the strings, 'S' and 'P' contain only lower-case alphabets.

3. Only the pattern will contain additional characters ‘*’ and ‘.’ along with alphabets.

Given that integers are read from a data stream. Your task is to find the median of the elements read so far.

Median is the middle value in an ordered integer list. If the size of the list is even there is no middle value. So the median is the floor of the average of the two middle values.

For example :

[2,3,4] - median is 3.
[2,3] - median is floor((2+3)/2) = 2.

You are given an array ‘ARR’ of integers. Your task is to find the length of the longest alternating subsequence.

Note:

A sequence a1, a2, .... an is called an alternating sequence if its elements satisfy one of the following relations : a1 < a2 > a3 < a4 > a5..... or  a1 > a2 < a3 > a4 < a5.

For example:

'ARR' = {3, 10, 1, 2, 30}, the longest alternating subsequence for this array can be {3, 10, 1, 30} or {3, 10, 2, 30}. Therefore, the answer will be 4.

You have been given an encoded string. Your task is to decode it back to the original string.

- An encoded string will be of the form <count>[encoded_string], where the 'encoded_string' inside the square brackets is being repeated exactly 'count' times. Note that 'count' is guaranteed to be a positive integer and can be greater than 9.
- There are no extra white spaces and square brackets are well-formed.

For example -

Input: 2[a]
“a” is encoded 2 times, hence the decoded string will be "aa".

Input: 3[a2[b]]
“b” is encoded 2 times, which decodes as 3[abb]. Now, "abb" is encoded 3 times, hence decoded string will be "abbabbabb".