Complete DSA Roadmap for Interview Preparation

Who this roadmap is for

This 12-week plan is designed for software engineers targeting product company interviews (SDE-1 to SDE-2 level). It assumes you know basic programming and can dedicate 2–3 hours daily. Adjust pace if you have more or less time, but do not skip the fundamentals.

Weeks 1–2: Arrays, strings, and two pointers

Build fluency with the most common interview patterns. Aim for 3–4 problems per day.

• Day 1–3: Array traversal, prefix sums, kadane's algorithm.
• Day 4–6: Two pointers (sorted arrays, palindromes, container with most water).
• Day 7–9: Sliding window (fixed and variable size).
• Day 10–12: String manipulation (anagrams, substrings, character frequency).
• Day 13–14: Review weak problems + 1 timed mock.
• Target: 40 problems, recognize pattern in under 3 minutes.

Weeks 3–4: Stacks, queues, linked lists, and hashing

These structures appear in medium problems across every company.

• Stacks: valid parentheses, monotonic stack, next greater element.
• Queues and deques: BFS foundations, sliding window maximum.
• Linked lists: reversal, cycle detection, merge sorted lists.
• Hash maps and sets: two-sum, grouping, frequency counting.
• Practice implementing each from scratch without IDE autocomplete.
• Target: 35 problems, clean implementation under 25 minutes.

Weeks 5–7: Trees and graphs

Tree and graph questions separate candidates who know patterns from those who memorize solutions.

• Week 5 — Trees: traversals (in/pre/post/level), BST operations, height and diameter.
• Week 6 — Trees advanced: LCA, serialize/deserialize, path sum problems.
• Week 7 — Graphs: BFS, DFS, topological sort, union-find, cycle detection.
• Learn to draw the tree/graph before coding every time.
• Practice 4–5 problems per day; trees and graphs need volume.
• Target: 50 problems, articulate BFS vs DFS trade-offs clearly.

Weeks 8–10: Dynamic programming

DP is the hardest topic for most candidates. Spend three full weeks — rushing here costs you onsite rounds.

• Week 8 — 1D DP: climbing stairs, house robber, coin change, LIS.
• Week 9 — 2D DP: grid paths, edit distance, knapsack variants.
• Week 10 — DP patterns: state machine, interval DP, partition problems.
• For each problem: define state, recurrence, base case, iteration order.
• If stuck for 30 min, read the solution, then re-solve from scratch next day.
• Target: 30 DP problems with spoken state-definition practice.

Week 11: Heaps, binary search, and bit manipulation

Fill gaps in high-frequency patterns before mock interview season.

• Heaps: top-K elements, merge K sorted lists, median from stream.
• Binary search: on arrays, on answer space (minimize maximum, capacity).
• Bit manipulation: XOR tricks, counting bits, power of two.
• Greedy: activity selection, interval scheduling, Huffman-style problems.
• Target: 25 problems across these topics.

Week 12: Mock interviews and weak area review

Shift from learning mode to performance mode. Simulate real interview conditions.

• Days 1–3: 2 timed mocks per day on InterviewVeda (coding + behavioral).
• Days 4–5: Review mistakes journal — re-solve every problem you failed in mocks.
• Days 6–7: Light review of core patterns, rest before real interviews.
• Practice on a plain text editor — no autocomplete, no run button.
• Record yourself explaining solutions aloud for communication practice.

System design basics (parallel track for SDE-2)

If you are targeting SDE-2 or senior roles, add 3–5 hours per week alongside the DSA plan from Week 5 onward.

• Learn: load balancers, caching, databases (SQL vs NoSQL), message queues.
• Practice: design URL shortener, chat system, news feed, rate limiter.
• Framework: requirements → estimation → API → data model → scaling → trade-offs.
• Read engineering blogs (Google SRE, Netflix, Uber) for real-world patterns.

How to track progress

Maintain a spreadsheet: problem name, pattern, difficulty, time taken, solved without hints (yes/no). Review weekly. If a pattern appears 3+ times in your mistakes journal, dedicate a half-day to it. Consistency over 12 weeks beats cramming over 2.