Key takeaways
- Tree traversals, BST and AVL insertion, heaps, hashing and infix to postfix carry most marks.
- Keep one table of sorting algorithms with best, average and worst time, space and stability.
- Each section has exam tips and formula boxes, and the last page lists the most asked practice questions.
- These are original Uncodemy revision notes, not official university notes; check your own syllabus.
About these Data Structures handwritten notes
This page offers Uncodemy's Data Structures notes as a free handwritten-style PDF. Data Structures is about storing and organising data so programs can search, insert and delete efficiently. The notes are written in short points with neat tables, labelled diagrams, boxed formulas and exam tips, so you can revise a full unit in one sitting instead of reading a long textbook chapter.
Please note: these are original Uncodemy revision notes. They follow the common syllabus that most Indian universities share for this subject, but they are not official university notes. Check your own university syllabus and add anything it lists that is missing here.
What's inside the Data Structures notes
The PDF is arranged in 9 sections plus a final page of most asked practice questions. The sections follow the usual unit order of a Data Structures syllabus, so you can map them to your own units quickly. Here is what each section covers.
Introduction and asymptotic notation
Types of data structures, abstract data types and a short note on Big-O, Omega and Theta for measuring cost.
Arrays and linked lists
Array addressing, singly, doubly and circular linked lists, insertion at the beginning with code, and array vs linked list.
Stack
Push and pop, stack using array and linked list, rules for infix to postfix conversion and step-by-step postfix evaluation.
Queue
Linear and circular queues with full and empty conditions, deque and priority queue.
Trees
Important facts for height h, inorder, preorder and postorder traversals, BST operations, AVL rotations, and B-tree and B+ tree of order m.
Heap
Min-heap and max-heap in an array, heapify, building a heap and heap sort.
Graphs
Adjacency matrix and adjacency list representation, and BFS and DFS traversal.
Hashing
Hash functions, collisions, chaining and open addressing with linear probing, quadratic probing and double hashing.
Searching and sorting summary
Linear and binary search, and bubble, selection, insertion, merge, quick and heap sort compared on time, space and stability.
Most asked questions (practice)
Ten exam-style questions, from reversing a linked list to comparing sorting algorithms.
How to use handwritten notes to revise Data Structures
Data Structures is learnt by drawing and tracing, so keep blank paper next to the notes and redraw every structure as it changes.
- Trace infix to postfix with the stack column shown at each step, for two expressions.
- Insert the same set of keys into a BST and an AVL tree, and draw each rotation.
- Build a max-heap from an array and then show each step of heap sort.
- Write the linked list insert, delete and reverse functions from memory, then check them against the notes.
A simple three-pass method works well with handwritten notes. In the first pass, read one section and underline only what you do not already know. In the second pass, close the notes and write the definitions, diagrams and steps for that section on a blank sheet, then compare and correct in a different colour. In the third pass, a day or two later, answer two or three exam-style Data Structures questions in timed conditions using only memory. Add your own examples and doubts in the margins so the PDF becomes your personal revision copy.
Formulas, diagrams and definitions to memorise
- Address of A[i][j] in row-major order: base + ((i x columns) + j) x element size.
- Tree facts: a binary tree of height h has at most 2^(h+1) - 1 nodes; n nodes means n - 1 edges.
- Heap array positions for index i (0-based): left child 2i + 1, right child 2i + 2, parent (i - 1) / 2.
- Circular queue full condition (rear + 1) mod size == front, and empty condition front == -1.
- The four AVL rotations (LL, RR, LR, RL) and the time complexity table of sorting algorithms.
Common mistakes that cost marks
- Popping operators in the wrong order during infix to postfix; respect precedence and associativity.
- Forgetting to update the balance factor after each AVL insertion.
- Losing the rest of the list when reversing a linked list because the next pointer was not saved.
- Calling quick sort stable; it is not stable in its usual form.
Exam focus: Data Structures topics that carry the most marks
These Data Structures topics come up in most university papers and in GATE.
- Tree traversals and building a tree from inorder and preorder.
- BST and AVL insertion with rotations, and B-tree basics.
- Heaps and heap sort.
- Infix to postfix, circular queue conditions, hashing with probing and sorting comparisons.
Typical long questions
- Compare arrays and linked lists, and write code to reverse a singly linked list.
- Convert an infix expression to postfix and prefix using a stack.
- Evaluate a postfix expression step by step.
- Explain a circular queue with full and empty conditions.
- Construct a binary tree from given inorder and preorder traversals.
- Insert keys into an AVL tree, showing all rotations.
- Explain collision resolution with a linear probing example.
Marks per question change between universities and years, so confirm the pattern on a recent official paper. In long answers, start with a definition, add a labelled diagram or table, explain the steps and finish with an example or comparison. Underline the key term in each answer and leave a line between steps, because examiners mark faster when the structure is easy to see.
A 7-day revision plan for Data Structures
- Day 1: Introduction and asymptotic notation, Arrays and linked lists.
- Day 2: Stack, Queue.
- Day 3: Trees, Heap.
- Day 4: Graphs, Hashing.
- Day 5: Searching and sorting summary.
- Day 6: redo the traces: infix to postfix, postfix evaluation, AVL insertion, heap sort and one hashing table with linear probing.
- Day 7: answer the most asked practice questions at the end of the notes from memory, then solve one official previous year paper in three hours and mark the units that cost you time.
Keep a single sheet of formulas, definitions and diagrams from the notes for the last hour before the exam, and do not start new topics on the final day.
Who these notes are for
- B.Tech CSE and IT students preparing for the semester Data Structures exam.
- BCA and MCA students with a data structures paper in C, C++ or Java.
- GATE CS aspirants revising trees, heaps and hashing.
- Students preparing for coding rounds who want the theory behind DSA problems.
The notes are a revision aid, not a first textbook. If a Data Structures topic is new to you, learn it from your prescribed book or class lectures first, then come back to the notes to compress and revise it. For practice, pair them with the Data Structures Important Questions PDF page and your university's official previous year papers. If your syllabus has a topic that is not covered here, you can ask for it through the handwritten notes request page linked below.
Download Data Structures Handwritten Notes PDF
Data Structures Handwritten Notes PDF (Free)
The PDF carries the same content as this page in a clean, print-ready layout, so you can read it offline and keep it for revision.
7 pages · 297 KB · PDF · Updated 5 Nov 2026