Top Data Structures and Algorithms Questions for Big Tech Interviews

Aditya Solanki | Aug 3, 2024 min read
Top Data Structures and Algorithms Questions for Big Tech Interviews

Preparing for a big tech interview can be daunting, especially when it comes to data structures and algorithms. These concepts form the foundation of many technical interviews, and mastering them is key to success. 💻

Most Commonly Asked Questions

1. Arrays and Strings

  • Problem: Find the first non-repeating character in a string.
  • Problem: Rotate an array by k positions.
  • Problem: Implement a function to check if two strings are anagrams.

Preparation Tips:

  • Practice traversing and manipulating arrays and strings.
  • Focus on understanding the time complexity of different approaches.
  • Familiarize yourself with common operations like sorting, searching, and hashing.

2. Linked Lists

  • Problem: Reverse a linked list.
  • Problem: Detect and remove a cycle in a linked list.
  • Problem: Merge two sorted linked lists.

Preparation Tips:

  • Understand how to manipulate pointers and nodes in a linked list.
  • Practice solving problems related to singly and doubly linked lists.
  • Focus on edge cases, such as empty lists and lists with one element.

3. Trees and Graphs

  • Problem: Implement a binary search tree (BST) and perform in-order traversal.
  • Problem: Find the lowest common ancestor (LCA) of two nodes in a BST.
  • Problem: Implement depth-first search (DFS) and breadth-first search (BFS) on a graph.

Preparation Tips:

  • Learn different tree traversals: in-order, pre-order, and post-order.
  • Practice solving problems involving binary trees, BSTs, and heaps.
  • Understand graph representations (adjacency list, adjacency matrix) and algorithms (DFS, BFS, Dijkstra’s).

4. Dynamic Programming

  • Problem: Solve the knapsack problem.
  • Problem: Find the longest increasing subsequence.
  • Problem: Calculate the minimum cost path in a grid.

Preparation Tips:

  • Master the concept of breaking down problems into subproblems.
  • Practice identifying overlapping subproblems and optimal substructure.
  • Work on memorization techniques to avoid recomputation.

5. Sorting and Searching

  • Problem: Implement quicksort and mergesort.
  • Problem: Find the median of two sorted arrays.
  • Problem: Search for a target value in a rotated sorted array.

Preparation Tips:

  • Understand the inner workings of different sorting algorithms.
  • Focus on binary search and its variations.
  • Practice solving problems that combine sorting and searching.

6. Hashing

  • Problem: Implement a hash map from scratch.
  • Problem: Find the longest substring without repeating characters.
  • Problem: Two-sum problem (find two numbers in an array that add up to a specific target).

Preparation Tips:

  • Get comfortable with hash tables and their operations.
  • Practice problems that involve key-value pair mapping.
  • Learn about collision handling techniques like chaining and open addressing.

How to Prepare

  1. Practice Consistently: Dedicate time daily to solve problems on platforms like LeetCode, HackerRank, and Codeforces.
  2. Understand the Fundamentals: Make sure you have a solid understanding of basic data structures and algorithms before moving on to complex problems.
  3. Mock Interviews: Practice mock interviews with peers or use platforms like Pramp to simulate real interview scenarios.
  4. Analyze Solutions: After solving a problem, review the solution’s time and space complexity and explore different approaches to improve efficiency.

N.B. Preparing for a big tech interview requires time, dedication, and a strategic approach. By focusing on the most commonly asked questions and honing your problem-solving skills, you can increase your chances of success. Remember, understanding the underlying concepts is just as important as finding the correct solution.

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