Data Structure - Interview Questions and Answers for 'Data structure' | Search Interview Question

Data Structure - Interview Questions and Answers for 'Data structure' - 74 question(s) found - Order By Rating

Q1. How to delete a node from linked list if u do not have head and only have a pointer to the element which has to be removed ?

Data Structure

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Q2. How many threads can access a concurrent hashmap when the hashcode is overridden and always returns a zero.

Data Structure

Ans. The impact of both cases (fixed hashcode or random hashcode for keys) will have same result and that is "unexpected behavior". The very basic need of hashcode in HashMap is to identify the bucket location where to put the key-value pair, and from where it has to be retrieved.

If the hashcode of key object changes every time, the exact location of key-value pair will be calculated different, every time. This way, one object stored in HashMap will be lost forever and there will be very minimum possibility to get it back from map.

For this same reason, key are suggested to be immutable, so that they return a unique and same hashcode each time requested on same key object.

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Q3. How to sort an ArrayList of objects

Data Structure

Ans. Using Collections.sort()

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Q4. What is the O notation for the ArrayList and List? And which one would you choose to insert item in the middle?

Data Structure

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Q5. What is Queue ?

Data Structure

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Q6. Write an algorithm to shift a linked list n positions.

Data Structure

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Q7. What is the time complexity and space complexity of reversing a Linked List ?

Data Structure

Ans. o(n) for time complexity
o(1) for space complexity

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Q8. What is Message Queue or MQ ?

Data Structure

Ans. Message queues implement an asynchronous communication pattern between two or more processes/threads whereby the sending and receiving party do not need to interact with the message queue at the same time. Messages placed onto the queue are stored until the recipient retrieves them. Message queues have implicit or explicit limits on the size of data that may be transmitted in a single message and the number of messages that may remain outstanding on the queue.

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Q9. Linked List related questions.

Data Structure

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Q10. How to build a blocking queue ?

Data Structure

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Q11. Implement a queue, using only stacks

Data Structure

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Q12. Write a Program to print all nodes of the data structure ?

Algorithm

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Q13. Implement a Stack with 2 threads in which one thread push data and another pop data.

Data Structure

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Q14. Detect a loop in a linked list

Data Structure

Ans. Work with two pointers on the linked list - a slow pointer (increments by one node) and a fast pointer (increments by two nodes). If both of these pointers meet at the same node, then there is a cycle in the linked list. Otherwise, no cycle.

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Q15. Write a Program to Find the maximum sum of the sub array ?

Data Structure

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Q16. Write a program to insert a value after a specific value in an array.

Data Structure

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Q17. Find the length of the non repeated numbers in an array.

Data Structure

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Q18. Find number of recycled pairs in n array.

Data Structure

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Q19. In an array every element is repeated twice except one, Find that element?

Data Structure

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Q20. Difference between Arrays and LinkedList ?

Data Structure

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Q21. Can you write code to copy one array into another ?

Data Structure

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Q22. What is hashing ?

data structure

Ans. Hashing is a technique to calculate the hash code for any object

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Q23. Why does an array need continuous memory locations and not Linked List ?

Data Structure

Ans. Array needs continuous memory location because it need to provide random access of it's elements which is not required for Linked List.

Array index acts as an offset from the base address and hence can retrieve the respective element using the expression Base Address + ( Index * Element Size ). This expression could only hold true if the elements are in continuous memory location.

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Q24. Why does an array index starts at 0 and not 1 ?

Data Structure

Ans. The array index starts with 0 because program locates an element using the expression ( BaseAddress + ( Index * size of array Element ), where index is used as an offset. As the starting address is actually the address of first element, the index of first element is used as 0 and so on.

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Q25. How will you implement your own custom hashmap and linkedlist ?

Data Structure

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Q26. What can we do if we need to retrieve Fibonacci value at a particular index faster ? Can we use Linked List ?

Data Structure

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Q27. Write a method that returns maximum depth of a tree ?

Algorithm

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Q28. What is the difference between pop and peek function of stack ?

Data Structure

Ans. pop method pulls the top element from the stack and then move the top to the next element whereas peek only get the top element but doesn't move the top.

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Q29. Write a program to sort a stack in ascending order You should not make any assumptions about how the stack is implemented The following are the only functions that should be used to write this program: push | pop | peek | isEmpty

Algorithm

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Q30. Describe how you could use a single array to implement three stacks

Algorithm

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