SDE - 1

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.

In a binary tree, a special node is a node that is the only child of its parent. The root of the tree is not special because it does not have a parent node. Node ‘1’ is always the root of the binary tree. Return an array/list containing the values of all special nodes in the tree.

Example:

Let’s say you have a binary tree as follows:-

Node 4 is a special node as it is the only child of node 2. Node 1 cannot be a special child as it does not have a parent. All the other nodes have a sibling i.e there parent has more than one child. Therefore return [4] as the answer.

Note:

Return the array/list containing special nodes in any order. 

You have been given an array of 'N' Integers. Find the length of the longest subsequence such that each adjacent element of the subsequence has at least one digit in common.

Note :

A sequence 'A' is a subsequence of a sequence 'B' if 'A' can be obtained from 'B' by deletion of several (possibly, zero) elements. For example, [3,1] is a subsequence of [3,2,1] and [4,3,1], but not a subsequence of [1,3,3,7] and [3,10,4].

You have been given an integer array/list(ARR) of size 'N'. It only contains 0s, 1s and 2s. Write a solution to sort this array/list.

Note :

Try to solve the problem in 'Single Scan'. ' Single Scan' refers to iterating over the array/list just once or to put it in other words, you will be visiting each element in the array/list just once.

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