Koo App Sde1 Interview Questions and Answers

Q1. 1. What is a doubly-linked list? And real-world applications.
Ans. 
A doubly-linked list is a data structure where each node contains a reference to both the previous and next nodes.
• Allows traversal in both directions

• Used in implementing LRU cache

• Used in browser history

• Used in undo-redo functionality
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Q2. 2. Advantage of doubly linked list over singly LL?
Ans. 
Doubly linked list allows traversal in both directions, while singly linked list only allows traversal in one direction.
• Doubly linked list allows for efficient deletion of nodes compared to singly linked list.

• Doubly linked list can be traversed in both forward and backward directions.

• Doubly linked list can be used to implement a stack or queue.

• Singly linked list requires less memory than doubly linked list.

• Doubly linke...read more
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Q3. 3. Applications of Graph Data Structure
Ans. 
Graph data structure is used in various applications such as social networks, routing algorithms, and recommendation systems.
• Social networks use graphs to represent users and their connections.

• Routing algorithms use graphs to find the shortest path between two points.

• Recommendation systems use graphs to analyze user behavior and suggest relevant items.

• Graphs are also used in computer networks, image processing, and mac...read more
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Q4. 4. Tree Traversals (Inorder, Preorder and Postorder)
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Q5. 5. Remove duplicate elements and sort related scenario-based questions. Have to discuss the approach and then have to code it.
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Q6. 6. Similar to bubble sort. Have to discuss the approach and then have to code it.
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Q7. 7. What is the difference between In-memory DB and MySQL?
Ans. 
In-memory DB stores data in RAM for faster access while MySQL stores data on disk.
• In-memory DB is faster than MySQL as it eliminates disk I/O operations.

• In-memory DB is suitable for real-time applications that require low latency.

• MySQL is suitable for applications that require data persistence and durability.

• In-memory DB may not be suitable for large datasets as it requires a lot of RAM.

• MySQL supports complex queries a...read more
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Q8. 8. SQL related basic questions
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Q1. 1. Difference between RDBMS and NoSQL
Ans. 
RDBMS is a structured database that uses SQL while NoSQL is a non-relational database that doesn't use SQL.
• RDBMS stores data in tables with predefined schema while NoSQL stores data in documents, key-value pairs, or graphs.

• RDBMS is good for complex queries and transactions while NoSQL is good for scalability and handling unstructured data.

• Examples of RDBMS include MySQL, Oracle, and SQL Server while examples of NoSQL i
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Q2. 2. What is indexing?
Ans. 
Indexing is the process of organizing data in a database or search engine to improve search efficiency.
• Indexing creates a data structure that allows for faster retrieval of information.

• It involves creating an index that maps the location of data in a database or search engine.

• Indexing can be done on various types of data, such as text, numbers, and dates.

• Examples of indexing methods include B-tree, hash, and bitmap ind
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Q3. 3. Scenario-based question: One employee table is there. We execute query One without indexing, one with indexing. What will be the difference?
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Q4. 4. Explain the internal working of the above question.
Ans. 
The question is unclear and requires clarification.
• The question is not specific about what 'above question' it is referring to.

• The term 'internal working' is also vague and needs to be defined.

• Without more information, it is impossible to provide a meaningful answer.
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Q5. 5. Print the right view of the binary tree. Have to discuss the approach and then have to code it.
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Q6. 6. Different modifications in the above question and then have to tell approaches like print left view of a binary tree.
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Q7. 7. Print internal nodes of a binary tree (internal nodes means except nodes present in the left and right view)
Ans. 
Print internal nodes of a binary tree (excluding left and right view nodes)
• Traverse the tree in post-order and check if the node has both left and right children

• If yes, then it is an internal node and print it

• If no, then continue traversing the tree

• Example: For the tree 1-2-4-5-3, the internal nodes are 2 and 4
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Q1. They ask you to introduce yourself, followed by questions regarding your background goals, strengths, etc.
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Q1. Senior taking technical round
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Q1. Manger Taking technical round
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Q1. Salary Discussion
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2 dsa questions of easy/medium

Q1. Asked two dsa questions of leetcodeeasy/medium
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Q1. Asked two dsa questions of leetcode easy/medium
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Q1. Asked one dsa question on tree and discussion on resume and dbms os
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Q1. Salary Discussion
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Q1. Techical questions and coding questions related profile.
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Q2. Basic concepts about your programming skills.
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Two pointer and sliding window

Q1. Delete nth node from end in linked list
Ans. 
To delete the nth node from the end in a linked list, we can use a two-pointer approach.
• Use two pointers, one to traverse the list and another to keep track of the nth node from the end.

• Move the second pointer n steps ahead of the first pointer.

• When the second pointer reaches the end of the list, the first pointer will be at the nth node from the end.

• Adjust the pointers to delete the nth node.
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Q2. Project discussion
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Easy to medium, can solve with leetcode medium

Q1. Number of islands count
Ans. 
Count the number of islands in a grid of '1's and '0's
• Iterate through the grid and for each '1' encountered, perform a depth-first search to mark all connected '1's as visited

• Increment the island count for each new island found

• Ensure to handle boundary cases and check for visited nodes
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Q2. First and last index of a particular element in an array
Ans. 
Find the first and last index of a specific element in an array of strings.
• Iterate through the array and keep track of the index of the first and last occurrence of the element.

• Return the first and last index once the iteration is complete.

• Example: Array ['apple', 'banana', 'apple', 'orange'], element 'apple' - First index: 0, Last index: 2.
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Q1. React, React Native Basics
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Q2. Coding Arrays & Objects
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