Deutsche Telekom SDE Interview Questions and Answers

Round duration - 180 minutes
Round difficulty - Hard

There was 1 round of 180 minutes which contains of 3 questions from DSA. the two question was of medium level but one question is of neither difficult nor medium level question based on tree

Q1. 
Longest Increasing Subsequence Problem Statement
Given an array of integers with 'N' elements, determine the length of the longest subsequence where each element is greater than the previous element. This...read more
Ans. 
Find the length of the longest strictly increasing subsequence in an array of integers.
• Use dynamic programming to keep track of the longest increasing subsequence ending at each element.

• Initialize an array to store the length of the longest increasing subsequence ending at each index.

• Iterate through the array and update the length of the longest increasing subsequence for each element.

• Return the maximum value in the ar...read more
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Q2. 
Bipartite Graph Problem
Check whether a given graph is bipartite or not. Return true if the graph's vertices can be divided into two independent sets, ‘U’ and ‘V’, such that every edge (‘u’, ‘v’) either c...read more
Ans. 
Check if a given graph is bipartite by dividing vertices into two independent sets.
• Use BFS or DFS to traverse the graph and assign colors to vertices to check for bipartiteness.

• If an edge connects vertices of the same color, the graph is not bipartite.

• Return true if all edges connect vertices of different colors, else return false.
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Q3. 
Count Inversions Problem Statement
Given an integer array ARR of size N containing all distinct values, determine the total number of inversions present in the array.
An inversion is defined for a pair o...read more
Ans. 
Count the total number of inversions in an integer array.
• Iterate through the array and for each pair of elements, check if the conditions for inversion are met.

• Use a nested loop to compare each element with all elements to its right.

• Keep a count of the inversions found and return the total count at the end.
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Round duration - 50 minutes
Round difficulty - Medium

In interview I was asked about some question related to Data structures , DBMS . Some output based question was asked and 2 coding problems was given to solve.

Q1. 
Return Subsets Sum to K Problem Statement
Given an integer array 'ARR' of size 'N' and an integer 'K', return all the subsets of 'ARR' which sum to 'K'.
Explanation:
A subset of an array 'ARR' is a tupl...read more
Ans. 
Given an array and an integer, return all subsets that sum to the given integer.
• Use backtracking to generate all possible subsets of the array.

• For each subset, check if the sum equals the given integer 'K'.

• Print the subsets that satisfy the condition.

• Example: For input [1, 2, 3] and K=3, subsets [1, 2] and [3] have sum 3.
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Q2. 
Boundary Traversal of Binary Tree
Given a binary tree of integers, your task is to print the boundary nodes of the binary tree in an anti-clockwise direction starting from the root node.
Note:
The boundary...read more
Ans. 
Boundary traversal of a binary tree in anti-clockwise direction starting from the root node.
• Implement a function to calculate the boundary traversal of a binary tree

• Include nodes from left boundary, leaf nodes, and right boundary in sequence

• Ensure only unique nodes are included in the output

• Print the boundary nodes separated by single spaces for each test case
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