Engineered for interviews.
Built for intuition.
247 hand-picked interview problems in the order I teach them — each with the key concept that cracks it, a video walkthrough, a 60-second Short and the companies that ask it.
No card, no catch. Problem #1 takes about ten minutes.
nums (sorted) = [2, 3, 5, 7, 9, 12, 14, 18] · target = 19
›2 + 18 = 20 > 19 → need smaller, move R left
When a problem mentions
a sorted array, pairs or triplets, or scanning in from both ends
reach for Two PointersArrays
- 247
- Hand-picked problems
- 14
- Topics, in order
- 22
- Video solutions
- 300+
- Companies tagged
What you get
Everything for a problem, on one row.
Every row of the sheet is a complete study kit — so you always know what to open next instead of tab-hopping across five sites.
Anatomy of a row
Reverse LinkedList
LinkedList + Recursion
Key concept
The idea that cracks it
Video + Short
On YouTube, live now
Companies
Where it's been asked
Tick · flag · note
Saved to your account
Learn it, then revise it
22
full video solutions
11
60-second Shorts
Watch the walkthrough when the idea is new. Watch the Short the night before your interview.
Dry-run visualizer · preview
Reverse LinkedList, one pointer move at a time.
Three pointers — prev, curr and next — flip every arrow in one pass. Visualizers for every problem are coming soon; videos and Shorts are live on YouTube today.
1prev ← null2curr ← head3while curr ≠ null:4 next ← curr.next5 curr.next ← prev6 prev ← curr7 curr ← next8return prev
prev starts at null — the reversed list is empty.
Company tags
See where every problem was asked.
- Amazon 196
- Microsoft 154
- Facebook 150
- Google 141
- Apple 110
- Bloomberg 109
- Adobe 96
- Uber 80
- Oracle 64
Filter the sheet by any of 301 companies.
Progress
Pick up exactly where you left off.
- Solved, per topic & difficulty
- Flagged for revision
- Private notes
Handwritten notes
Coming soonExam-style notes for every problem.
Clean, one-page notes you can revise from — rolling out topic by topic.
Dry-run visualizer · coming soon
Stop dry-running in your head.
Every problem will get a step-by-step visualizer: the current line highlighted, pointers moving across the array, the hash map filling up, and a plain-English explanation for each step.
Try the preview — that's Two Sum, problem #1 on the sheet.
Solve Two Sum1vector<int> twoSum(vector<int>& nums, int target) {2 unordered_map<int, int> seen;3 for (int i = 0; i < nums.size(); i++) {4 int need = target - nums[i];5 if (seen.count(need))6 return {seen[need], i};7 seen[nums[i]] = i;8 }9 return {};10}
nums · target = 9
seen · value → index
Create an empty hash map `seen` (value → index).
The syllabus
14 topics, one sequence.
- 01Start here
Contiguous cells — traverse indices 0 → 4 in order
Arrays
Hashing, two pointers, prefix sums and in-place rearrangement — the foundation every other topic builds on.
- 0210 problems
Character sequence — iterate s[0] → s[4]
Strings
Frequency maps, sliding windows and palindrome expansion on character sequences.
- 0315 problems
Halve the sorted range at every step
Binary Search
Halving the search space — on sorted arrays, rotated arrays and on the answer itself.
- 0422 problems
Circular nodes linked by pointers — traverse head → null
Linked List
Pointer manipulation: reversal, fast & slow pointers, dummy nodes and in-place merging.
- 0520 problems
Last in, first out — traverse from top down
Stack
LIFO thinking — bracket matching, monotonic stacks and expression evaluation.
- 0612 problems
Call down to base case f(0), then unwind back up
Recursion
Breaking a problem into smaller copies of itself — the base for backtracking, trees and DP.
- 0712 problems
Explore a branch, backtrack on a dead end, try the next
Backtracking
Choose, explore, un-choose — subsets, permutations and constraint-satisfying boards.
- 0824 problems
Hierarchical tree — first BFS levels, then DFS depth
Binary Tree
DFS and BFS traversals, views, depths, paths and lowest common ancestors.
- 0911 problems
Ordered tree (L < root < R) — BFS levels & sorted DFS
Binary Search Tree
Exploiting left < root < right for search, validation, deletion and ordered traversal.
- 1013 problems
Complete heap tree — BFS array order & DFS branches
Heaps
Priority queues for top-K, k-way merges, running medians and scheduling.
- 115 problems
Prefix tree — BFS by depth, DFS word by word
Trie
Prefix trees for dictionary lookups, autocomplete and word search.
- 1215 problems
Scan 0 → 4 and lock in the best choice at each step
Greedy
Locally optimal choices — intervals, reachability and resource assignment.
- 1342 problems
Vertices and edges — ripple with BFS, plunge with DFS
Graphs
Traversals, cycle detection, topological sort, shortest paths, MST, DSU and Tarjan.
- 1425 problems
Fill dp[0 → 4] in order by reusing earlier states
Dynamic Programming
Overlapping subproblems — 1D, grid, string, knapsack and interval DP.
Abhishek Aggarwal
AI Engineer · DSA educator
Meet the creator
Hi, I'm Abhishek 👋
I'm an AI engineer with over two years of industry experience, and I've spent the last four years solving DSA problems and teaching them to students.
This sheet is the order I actually teach in — every problem chosen because it introduces a pattern or sharpens one, with the key concept written next to it so you learn to recognise it, not memorise it.
I'm recording a video and a Short for every problem, and building a visualizer so you can watch each solution run step by step.
- 4+ yrs
- Solving & teaching DSA
- 2+ yrs
- AI engineer in industry
- 1000+
- LeetCode problems solved
- Guardian
- LeetCode contest rating
Join in
Learn together.
New videos, Shorts and DSA breakdowns — pick your platform and follow along.
Your first ten minutes
Ready to start?
Problem #1 is waiting.
Make a free account, open the sheet and solve your first problem tonight. Every tick, flag and note is saved, so tomorrow you pick up exactly where you stopped.
- Free, forever
- 247 problems, in order
- Progress synced to your account
- 01Create your account20 seconds · no card
- 02Solve Two SumHash Map (Complement finding) · about 10 minEasy
- 03Tick it, keep going246 more, each building on the last
FAQ
Frequently asked questions.
Find your starting point and learn how to get the most out of the sheet.
Yes. The full sheet, video solutions, Shorts and progress tracking are free. You just need a free account to open the sheet.
Anyone preparing for coding interviews or placements — from students starting DSA to working engineers switching to product companies. The topics start from the basics and build up.
Yes. A free account takes about 20 seconds and unlocks the full sheet. Your ticks, revision flags and notes are saved to it, so you can switch devices and pick up where you left off.