Deutsche Telekom Digital Labs React Js Frontend Developer Interview Questions and Answers

Round duration - 90 Minutes
Round difficulty - Easy

It was in in the evening at 5pm, it was simple with 20 mcqs on java,dbms,os.sql. And 2 coding questions.

Q1. Find Duplicates In Array
You are given an array/list 'ARR' consisting of N integers, which contains elements only in the range 0 to N - 1. Some of the elements may be repeated in 'ARR'. You...read more
Ans. Sorting
1. The most trivial approach would be to sort the array/list ‘ARR’ and then return the duplicates.
2. After sorting the array in non-decreasing order, do the following for all the elements from i = 0 to i = n - 2:
   • If ARR[i] == ARR[i + 1], then add ARR[i] to the the output list.
   • While ARR[i] == ARR[i + 1], do i = i + 1, since we don’t want to add the same duplicate elements again and again.
   • Else continue.
3. After this loop, w...read more
Answered by CodingNinjas
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Round duration - 45 Minutes
Round difficulty - Medium

It was afternoon.2 interviewers are present. What are forms and how to create forms in HTML? What are Entities and Relationships? What is an Alias in SQL?

Q1. Reverse the String
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...read more
Ans. Optimal Solution
• Traverse the string and swap the first character with the last character, the second character with the second last character and so on.
• Basically, you need to swap the i-th character with the (N-i-1)-th character where N is the length of the string and 0-based indexing is considered.
Space Complexity: O(1)Explanation:
O(1).
 
In the worst case, only constant extra space is required.
Time Complexity: O(...read more
Answered by CodingNinjas
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Q2. Implement Stack With Linked List
You need to implement the Stack data structure using a Singly Linked List.
Create a class named 'Stack' which supports the following operations(all in O(1) time):
...read more
Ans. Best Approach
1. Maintain a linked list. Keep track of its head, and size at all times, and update them accordingly whenever a new operation is performed.
2. Following is the way we can implement all functions of the stack using linked list:
   1. First, initialize a head node, and the size of the list as NULL and 0 respectively.
   2. Then for push function, insert new elements at the head of the list, i.e. the new element will become the ...read more
Answered by CodingNinjas
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