📌 Introduction
Every year, thousands of students prepare for coding interviews and placements. While there are thousands of problems online, the truth is:
👉 A handful of DSA problems keep getting repeated across companies like TCS, Infosys, Wipro, Amazon, Microsoft, and Google.
If you master these repeated interview problems, you cover 60–70% of coding test patterns.
🧩 Most Repeated DSA Problems
Here’s a curated list of frequently asked DSA problems, categorized by topic.
🔢 Arrays
Two Sum Problem (Find indices of two numbers that add up to a target).
Kadane’s Algorithm (Maximum subarray sum).
Rotate Array (Left/Right rotation).
Find Missing Number in an array from 1 to n.
Majority Element (appearing more than n/2 times).
💡 Common in Infosys, TCS, Accenture, Wipro interviews.
🔡 Strings
Check Palindrome String.
Anagram Check (two strings contain same characters).
Longest Common Prefix among given strings.
Valid Parentheses (balanced brackets).
Substring Search (implement strstr/IndexOf).
💡 Frequent in service-based companies and entry-level rounds.
🔗 Linked List
Reverse a Linked List (Iterative + Recursive).
Detect a Cycle (Floyd’s Cycle Detection).
Merge Two Sorted Linked Lists.
Find Middle Element of Linked List.
Remove Nth Node from End.
💡 Infosys, Tech Mahindra, and Amazon often ask these.
📚 Stack & Queue
Implement Stack/Queue using arrays or linked list.
Next Greater Element.
Evaluate Postfix/Prefix Expression.
LRU Cache Implementation.
Sliding Window Maximum.
💡 Popular in Flipkart, Amazon, and Microsoft interviews.
🌳 Trees
Binary Tree Traversals (Inorder, Preorder, Postorder).
Height of a Tree.
Lowest Common Ancestor (LCA).
Diameter of a Tree.
Check if a Tree is Balanced.
💡 Asked in Amazon, Adobe, and Microsoft interviews.
🌐 Graphs
BFS & DFS Traversals.
Detect Cycle in Graph.
Shortest Path (Dijkstra’s Algorithm).
Minimum Spanning Tree (Prim/Kruskal).
Topological Sorting.
💡 Google, Microsoft, and Amazon love graph problems.
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