Wissen Technology Interview Questions, Process, and Tips

Paper pen coding test

Q1. Easy-medium level sliding window problem
Ans. 
Find the maximum sum of a subarray of size k in an array of integers.
• Use a sliding window approach to keep track of the sum of the current subarray.

• Slide the window by adding the next element and subtracting the previous element.

• Keep track of the maximum sum encountered so far.

• Return the maximum sum found.
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Q2. Easy-medium level array problem
Ans. 
Find the longest common prefix among an array of strings.
• Iterate through the characters of the first string and compare with other strings.

• Stop when a character doesn't match or reach the end of any string.

• Return the prefix found so far.
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Q3. Gave me a condition and asked what data structure i would use. Problem was related to data retrieval so we would use hashmaps.
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Q4. They also asked sql queires and dbms related concepts (ACID, etc)
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Q1. Write a program to merge 2 sorted list with n+m complexity
Ans. 
Merge two sorted lists with n+m complexity
• Create a new list to store the merged result

• Iterate through both lists simultaneously and compare elements

• Add the smaller element to the new list and move to the next element in that list

• Continue until all elements from both lists are merged
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Q2. From the employee table find out the employee list whose salary is highest in the department
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Q3. Singleton design patterns
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Q4. What is dependency injection
Ans. 
Dependency injection is a design pattern where components are given their dependencies rather than creating them internally.
• Dependency injection helps in achieving loose coupling between classes.

• It allows for easier testing by providing a way to mock dependencies.

• There are three types of dependency injection - constructor injection, setter injection, and interface injection.
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Q5. N+1 problem of hibernate
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The n+1 problem in Hibernate occurs when a query results in multiple individual queries being executed for each row fetched.
• Occurs when a query fetches a collection and then for each element in the collection, another query is executed to fetch related data

• Can be resolved by using fetch joins or batch fetching to reduce the number of queries

• Improves performance by reducing the number of database round trips
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Five MCQs, 2 moderate-level+1 hard level coding,2 SQL queries.

Hard-level 6 Data structure based questions to write the code.

Q1. Flattenedarray code
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Q2. Nested array objects to single array.
Ans. 
Convert nested array objects to single array of strings.
• Iterate through the nested arrays and flatten them into a single array.

• Use recursion to handle multiple levels of nesting.

• Example: [["a", "b"], ["c", "d"]] -> ["a", "b", "c", "d"]
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Q1. Reverse the list node with head node having multiple values.
Ans. 
Reverse a list node with multiple values in Java.
• Create a new linked list to store the reversed nodes.

• Traverse the original list and add each node to the front of the new list.

• Update the head node of the original list to point to the new list.
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Q2. Hard-level string question to write the code.
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Q1. Advanced Java and database
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Q2. Advanced Data structures
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HackerRank assessment

Q1. Java Streams related questions
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Q2. EASY TO Medium Level of DSA questions
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