Most Asked DSA Interview Practice Questions

Data Structures and Algorithms (DSA) rounds are a core part of technical interviews at almost every product-based company. Below is a curated set of the questions that show up most often, grouped by topic so you can practice systematically.

Arrays & Strings

• Find the maximum subarray sum (Kadane's Algorithm).
• Two Sum — find pair of indices that add up to a target.
• Reverse a string / check if a string is a palindrome.
• Merge two sorted arrays in place.
• Find the missing number in an array of 1 to n.

Linked Lists

• Reverse a singly linked list (iterative and recursive).
• Detect a cycle using Floyd's Cycle Detection.
• Merge two sorted linked lists.
• Find the middle node in a single pass.

Trees & Graphs

• Level order (BFS) and DFS traversals of a binary tree.
• Check if a binary tree is height-balanced.
• Find the lowest common ancestor of two nodes.
• Detect a cycle in a directed/undirected graph.
• Implement Dijkstra's shortest path algorithm.

Sorting & Searching

• Implement Quick Sort and Merge Sort from scratch.
• Binary search and its variations (first/last occurrence).
• Search in a rotated sorted array.

Dynamic Programming

• 0/1 Knapsack Problem.
• Longest Common Subsequence.
• Coin change / minimum coins problem.
• Longest Increasing Subsequence.

Preparation Tips

• Focus on understanding patterns (two pointers, sliding window, recursion, DP) rather than memorizing solutions.
• Always state time and space complexity after solving a problem.
• Practice explaining your approach out loud before coding.