DSA Preparation Guide: Complete Roadmap for Placements
Data Structures and Algorithms is the most crucial skill for cracking coding interviews at product companies. Whether you're targeting FAANG, startups, or service companies, DSA forms the backbone of technical interviews. Here's your complete preparation guide.
How Much DSA Do You Really Need?
| Company Type | DSA Level Required | Focus Areas |
|---|---|---|
| Service (TCS, Infosys) | Basic-Medium | Arrays, Strings, Basic logic |
| Product (Flipkart, Swiggy) | Medium-Hard | All DS, DP, Graphs |
| FAANG (Google, Amazon) | Hard | Everything + System Design |
| Startups | Medium | Practical coding + DS basics |
Topic-wise Preparation Guide
HIGH PRIORITY Arrays & Strings
Topics: Two pointers, sliding window, prefix sum, matrix operations, string manipulation
Questions to solve: 50-70 questions
Must-do problems: Two Sum, Maximum Subarray, Best Time to Buy Stock, Container With Most Water, Longest Substring Without Repeating
HIGH PRIORITY Linked Lists
Topics: Singly/Doubly linked list, fast-slow pointers, reverse, merge, detect cycle
Questions to solve: 20-30 questions
Must-do problems: Reverse Linked List, Detect Cycle, Merge Two Lists, Remove Nth Node, Palindrome Check
HIGH PRIORITY Stacks & Queues
Topics: Stack operations, monotonic stack, queue implementations, deque, priority queue
Questions to solve: 25-35 questions
Must-do problems: Valid Parentheses, Next Greater Element, Min Stack, Implement Queue using Stack
HIGH PRIORITY Binary Trees & BST
Topics: Traversals, construction, BST operations, LCA, views, path problems
Questions to solve: 40-50 questions
Must-do problems: Inorder/Preorder/Postorder, Level Order, Max Depth, Validate BST, Lowest Common Ancestor
HIGH PRIORITY Recursion & Backtracking
Topics: Base cases, recursion tree, subset generation, permutations, N-Queens
Questions to solve: 30-40 questions
Must-do problems: Subset/Combination Sum, Permutations, N-Queens, Sudoku Solver, Word Search
MEDIUM PRIORITY Sorting & Searching
Topics: Quick sort, Merge sort, Binary search variants, search in rotated array
Questions to solve: 25-35 questions
Must-do problems: Binary Search, Search in Rotated Array, Find First/Last Position, Merge Intervals
MEDIUM PRIORITY Hashing
Topics: HashMap operations, frequency count, two sum patterns, anagrams
Questions to solve: 20-30 questions
Must-do problems: Two Sum, Group Anagrams, Longest Consecutive Sequence, Subarray Sum Equals K
MEDIUM PRIORITY Dynamic Programming
Topics: 1D/2D DP, Knapsack variants, LCS, LIS, Matrix chain, DP on strings
Questions to solve: 50-70 questions
Must-do problems: Climbing Stairs, Coin Change, Longest Common Subsequence, 0/1 Knapsack, Edit Distance
MEDIUM PRIORITY Graphs
Topics: BFS, DFS, Dijkstra, Topological sort, Union Find, Cycle detection
Questions to solve: 30-40 questions
Must-do problems: Number of Islands, Clone Graph, Course Schedule, Shortest Path, Detect Cycle
LOWER PRIORITY Heaps & Tries
Topics: Min/Max heap, K-largest/smallest, Trie operations, word search
Questions to solve: 15-25 questions
Must-do problems: Kth Largest Element, Merge K Sorted Lists, Implement Trie, Word Search II
Recommended Schedule
3-Month Plan (For thorough preparation)
| Month | Topics | Questions/Day |
|---|---|---|
| Month 1 | Arrays, Strings, Linked Lists, Stacks, Queues | 3-4 questions |
| Month 2 | Trees, Recursion, Backtracking, Searching, Sorting | 3-4 questions |
| Month 3 | DP, Graphs, Heaps, Revision + Mock interviews | 3-4 questions |
1-Month Crash Course (Intensive)
| Week | Topics | Questions/Day |
|---|---|---|
| Week 1 | Arrays, Strings, Hashing, Two Pointers | 5-6 questions |
| Week 2 | Linked Lists, Stacks, Trees | 5-6 questions |
| Week 3 | Recursion, DP basics, Binary Search | 5-6 questions |
| Week 4 | Graphs, Revision, Mock tests | 5-6 questions |
Best Resources
Problem Solving Platforms
- LeetCode - Best for interview prep (do Blind 75, Neetcode 150)
- GeeksforGeeks - Great for theory + practice
- InterviewBit - Structured path
- CodeStudio (Striver SDE Sheet) - Curated problems
- HackerRank - Good for beginners
Video Resources
- Striver (Take U Forward) - Best DSA course in Hindi/English
- NeetCode - Excellent LeetCode explanations
- Abdul Bari - Algorithm fundamentals
- Aditya Verma - Best DP playlist
💡 Problem-Solving Tips
- Understand before coding: Spend 5-10 mins understanding the problem
- Think of approach first: Don't jump to coding immediately
- Start with brute force: Optimize after
- Dry run: Trace through examples before submitting
- Learn from solutions: If stuck for 30+ mins, look at solutions
- Revise: Solve the same problem after 2-3 days
Common Mistakes to Avoid
- Jumping to hard problems: Build foundation with easy first
- Not understanding time complexity: Learn Big O notation properly
- Skipping recursion: It's the foundation for DP and backtracking
- Memorizing solutions: Understand patterns, not specific problems
- Not practicing under time pressure: Do timed contests
- Ignoring edge cases: Empty inputs, single elements, large inputs
Interview Day Tips
- Clarify the problem before coding
- Discuss your approach with the interviewer
- Think out loud - show your thought process
- Start with brute force, then optimize
- Write clean, readable code
- Test with examples before submitting
- Handle edge cases
- If stuck, ask for hints - it's okay!
DSA preparation is a marathon, not a sprint. Consistency beats intensity. Solve problems daily, understand patterns, and you'll be ready to crack any coding interview. All the best! 🚀