Software Engineer

Swapping 2 numbers without any 3rd variable.

You are given a string 'STR'. The string contains [a-z] [A-Z] [0-9] [special characters]. You have to find the reverse of the string.

For example:

 If the given string is: STR = "abcde". You have to print the string "edcba".

follow up:

Try to solve the problem in O(1) space complexity. 

Given two strings ‘STR’ and ‘PTR’. Find all the starting indices of ‘PTR’ anagram substring in ‘STR’. Two strings are anagram if and only if one string can be converted into another string by rearranging the character.

For example, ‘ABCD’ and ‘ACBD’ are two anagram strings because ‘ACBD’ can be converted into ‘ABCD’ by rearranging the ‘B’ and ‘C’. ’ABA’ and ‘ABB’ are not anagram because we can’t convert ‘ABA’ to ‘ABB’ by rearranging the characters of particular strings.

‘ABACD’ and ‘CABAD’ are anagram because ‘ABACD’ can be converted into ‘CABAD’ by rearranging the first ‘A’ with ‘C’ and second ‘A’ with ‘B’.

Note:

Strings ‘STR’ and ‘PTR’ consist only of English uppercases.

Length of string ‘STR’ will always be greater than or equal to the length of string ‘PTR’.

The index is ‘0’ based.

In case, there is no anagram substring then return an empty sequence.

Explanation:

For example, the given ‘STR’ is ‘BACDGABCD’ and ‘PTR’ is ‘ABCD’. Indices are given

0-3 in ‘STR’ index 0,1,2,3 are ‘BACD’ and it is an anagram with ‘ABCD’
1-4 in ‘STR’ index 1,2,3,4 are ‘ACDG’ and it is not anagram with ‘ABCD’
2-5 in ‘STR’ index 2,3,4,5 are ‘CDGA’ and it is not anagram with ‘ABCD’
3-6 in ‘STR’ index 3,4,5,6 are ‘DGAB’ and it is not anagram with ‘ABCD’
4-7 in ‘STR’ index 4,5,6,7 are ‘GABC’ and it is not anagram with ‘ABCD’
5-8 in ‘STR’ index 5,6,7,8 are ‘ABCD’ and it is an anagram with ‘ABCD’

Hence there are 2 starting indices of substrings in the string ‘STR’ that are anagram with given ‘PTR’  which are index 0 and 5.

You are given two strings which are expressions in variables. You need to compare and tell if they are similar or different. You need to return “YES” for the same expressions and “NO” for different expressions. The expressions consist of lowercase alphabets, ‘+’, ‘-’ and ‘(‘, ‘)’. It may be assumed that there are at most 26 operands from ‘a’ to ‘z’.

Two expressions will be said as similar if they have the same set of operands and when some values are given to these operands, then both the expressions give the same result.

For example:

If the first expression is: (a + (b + c)) and the second expression is: a + b + c. The expressions are the same because if they are evaluated, they will give the same output. So the answer is “YES”.

Note:

You can assume that any expression is evaluated according to the BODMAS rule.

You are given an array/list 'ARR' storing values of 'N' nodes of a binary tree.

Your task is to construct a complete binary tree from the given array in level order fashion, i.e. elements from left in the array will be filled in the tree level-wise starting from level 0.

A Binary Tree is a Complete Binary Tree if all the levels are completely filled except possibly the last level and the last level has all nodes as left as possible.

For example, the following binary tree is a complete binary tree:

Note:

You need to return the root of the binary tree, the tree will be printed in level order format.

You have been given a string 'S' which only consists of lowercase English-Alphabet letters.

Your task is to find the shortest(minimum length) substring of 'S' which contains all the characters of 'S' at least once. If there are many substrings with the shortest length, then find one which appears earlier in the string i.e. substring whose starting index is lowest.

For example-

If the given string is S = "abcba", then the possible substrings are "abc" and "cba". As "abc" starts with a lower index (i.e. 0, "cba" start with index 2), we will print "abc" as our shortest substring that contains all characters of 'S'.

What is the event loop and event queue?