Interview questions. Data Structures and Algorithms (DSA). Ten categories. Entry level

In entry-level interviews, especially for software engineering roles, Data Structures and Algorithms (DSA) questions are quite common. Here's a breakdown of the types of DSA questions typically asked:


🔹 1. Arrays and Strings

Common Questions:


Find the maximum subarray sum (Kadane's Algorithm)


Two Sum / Three Sum


Rotate an array


Merge two sorted arrays


Check for anagram or palindrome


🔹 2. Linked Lists

Common Questions:


Reverse a linked list


Detect a cycle in a linked list (Floyd’s cycle detection)


Merge two sorted linked lists


Find the middle node


Remove nth node from end


🔹 3. Stacks and Queues

Common Questions:


Implement a stack using queues (and vice versa)


Next Greater Element


Valid Parentheses


Min Stack


Sliding Window Maximum


🔹 4. Trees and Graphs

Common Questions:


Inorder, Preorder, Postorder traversal


Level-order traversal (BFS)


Check if a binary tree is balanced or symmetric


Lowest Common Ancestor


DFS/BFS in graphs, Cycle detection


🔹 5. Recursion and Backtracking

Common Questions:


Generate all subsets/combinations/permutations


N-Queens


Sudoku solver


Word search in a grid


🔹 6. Searching and Sorting

Common Questions:


Binary search and its variations (e.g., lower bound, upper bound)


Merge sort, Quick sort basics


Search in a rotated sorted array


Kth largest/smallest element


🔹 7. Hashing / Hash Tables

Common Questions:


Two Sum / Subarray Sum Equals K


Group Anagrams


Longest Consecutive Sequence


LRU Cache (design-based)


🔹 8. Dynamic Programming (DP)

Common Questions:


Fibonacci (recursion vs memoization vs tabulation)


0/1 Knapsack


Longest Common Subsequence / Substring


Longest Increasing Subsequence


Coin Change problem


🔹 9. Greedy Algorithms

Common Questions:


Activity selection


Fractional knapsack


Jump Game


Gas Station


🔹 10. Sliding Window & Two Pointers

Common Questions:


Maximum sum subarray of size K


Longest substring with k distinct characters


Container with most water


Trapping rain water


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