Tree Traversal Pseudocode PQ

Duration: 7 min

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Inside: a video lesson and guided study material.

Module outline

  1. About Course: About the Course
  2. Paper 2 | Digital Logic: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Number System, Number Representation, Floating Point Rep
  3. Paper 2 | Computer Organization And Architecture: Basics of COA, Cache Memory Organization, Input Output Organisation, Pipelining, Control Unit Design, Instr Formats & Modes, Programming the Basic Computer
  4. Paper 2 | Analog And Digital Communication: Introduction to Communication Systems & Random Signals, Analog Communication Systems, Information Theory & Digital Communication Fundamentals, Digital Modulation & Detection Techniques, Error Control, Synchronization & Multiple Access Techniques
  5. Paper 2 | Programming in C: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling
  6. Paper 2 | Data Structures And Programming: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing, Java, OOPS with C++, Java Fundamentals, Array, String, IO & References
  7. Paper 2 | Algorithms: Algorithm Analysis, Sorting Algorithms, Time Complexity Analysis, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos
  8. Paper 2 | Compiler Design: Intro to Compilers, Lexical Analysis, Grammar & CFG, Syntax Analysis: Top-Down, Syntax Analysis: Bottom-Up, Semantic Analysis & SDT, Intermediate Code Gen, Code Optimization, Run Time Environment
  9. Paper 2 | Operating System: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Threads & Process Creation, Deadlock, Memory Management, Virtual Memory, Disc Scheduling, File Management, Unix OS, Linux OS
  10. Paper 2 | Databases: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, Relational Algebra, SQL, Relational Calculus, File Organization & Indexing, Transaction Management, Concurrency Control
  11. Paper 2 | Information Systems and Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management
  12. Paper 2 | Computer Networks: Introduction to CN, Data Communication, DLL: Access Control, DLL: Flow Control, DLL: Error Control, DLL: Framing, Data Link Layer - Ethernet, Net Layer: IPv4 & Proto, Net Layer: IP Addressing, Net Layer:Routing Protocol, Transport Layer Services, TL: Congestion & UDP, Application Layer, Hardware Basics
  13. Paper 2 | Internet & Web Technologies: Website, Browser & Services, Internet Fundamentals, Web Design & Development, Protocols & Services, Web Publishing & Hosting, Server Side & Security, Emerging Technologies, HTML Basics, JavaScript-Basics, CSS, XML, HTML5
  14. Paper 2 | Cyber Security And Emerging Technologies: Emerging Tech Trends, Internet of Things
  15. Paper 2 | Cloud Technology: Cloud Computing
  16. Paper 2 | Probability and statistics: Probability, Statistics
  17. Paper-1 English: Vocabulary, Preposition, Articles, Comprehension / Reading Comprehension / Unseen Passages (Critical Reasoning) (Paragraph Questions), Sentence Re-arrangements (Para Jumbles) (Narrative Sequencing), Sentence Correction (Error Correction), Sentence Completion (Fill in the blanks), Cloze Test (Cloze Passage), Sentence Construction
  18. Paper 1 General Mental Ability & Logical reasoning: Ratio and Proportion (Ratios), Divisibility Rules, Data Interpretation, Mixture and Alligation, Permutation and Combination, Logarithm, Number System, HCF LCM, Sequence and Series (Series), Speed Time and Distance, Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Data Sufficiency, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Percentage, Average, Powers and Exponents (Surds and Indices), Algebra, Profit and Loss, Simple Interest and Compound Interest, Time and Work, Pipe and Cistern, Mensuration and Geometry, Mental Ability, Age Problems, Partnership, Arithmetic, Speed Mathematics and Basic Mathematics, Syllogisms, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Seating Arrangements, Blood Relations, Directions (Direction Test), Analytical Reasoning (Counting Figures Reasoning), Puzzle Solving (Puzzles), Calendar, Clock, Cubes & Dices, Selection Decision Table (Decision Making), Logical Sequence Of Words, Venn Diagram, Analogy
  19. Paper-1 General Knowledge & Current Affairs: State Wise GK, History, Geography, GK- Current Affairs, Static General Knowledge
  20. Full Length Mock Test:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

The video lecture analyzes a recursive C function named `what` designed to traverse a binary tree. The instructor begins by displaying the code, which contains three `printf` statements and two recursive calls to `what` for the left and right children. He draws a sample binary tree on the whiteboard with a root node of value 1, a left child 2 (which has a left child 4), and a right child 3. The instructor then performs a step-by-step trace of the function execution. He demonstrates that for every node visited, the data is printed three times: once before the left child recursion, once between the left and right child recursions, and once after the right child recursion. By following the call stack, he derives the final output sequence: 1 2 4 4 4 2 2 1 3 3 3 1. The lesson emphasizes understanding the order of operations in recursive tree traversals.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The video opens with the code snippet for the function `void what(struct Bnode *t)`. The instructor introduces the problem of determining the function's behavior. He draws a binary tree on the right side of the screen, starting with a root node labeled 1. He adds a left child labeled 2 and a right child labeled 3. He further extends the tree by adding a left child labeled 4 to node 2. The instructor begins tracing the function by writing `what(1)` on the board, indicating the initial call with the root node. He underlines the first line of code inside the `if (t)` block, which is `printf("%d', t->data);`, explaining that this will print the data of the current node.

  2. 2:00 – 5:00 02:00-05:00

    The instructor continues the trace by underlining the next line, `what(t->LC);`, which represents a recursive call to the left child. He writes `what(2)` below `what(1)` to show the next step in the recursion. Inside the call for node 2, he explains that the data 2 is printed first. Then, the function calls `what(t->LC)` again, moving to node 4. For node 4, the data 4 is printed. Since node 4 has no left child, `what(NULL)` is called and returns immediately. The function then prints 4 again (the second `printf`), calls `what(t->RC)` (which is NULL and returns), and finally prints 4 a third time. The instructor writes the sequence `4 4 4` on the board to represent the output for node 4. Back in node 2, after the left child returns, the second `printf` prints 2 again. The right child call is NULL, so it returns, and the final `printf` prints 2 a third time.

  3. 5:00 – 7:17 05:00-07:17

    The trace returns to the root node 1. After the left subtree (node 2) finishes, the second `printf` in the root function executes, printing 1 again. Next, the function calls `what(t->RC)`, moving to the right child, node 3. The instructor explains that node 3 follows the same pattern: print 3, call left (NULL), print 3, call right (NULL), print 3. This results in the sequence `3 3 3`. Finally, the function returns to the root node 1 one last time, where the final `printf` statement executes, printing 1 for the third time. The instructor writes the complete output sequence on the board: `1 2 4 4 4 2 2 1 3 3 3 1`. He concludes by summarizing that the function prints each node's data three times in a specific order: pre-order, in-order, and post-order relative to the recursive calls.

The lecture provides a clear, visual method for tracing recursive functions on binary trees. By breaking down the code into its constituent parts—printing data and making recursive calls—the instructor shows how the execution flow determines the output. The key learning point is that the position of `printf` statements relative to the recursive calls dictates the traversal order. In this specific case, the function performs a custom traversal where every node is visited and printed three times: before descending left, between left and right descents, and after descending right. This reinforces the concept that recursive functions execute code sequentially, and the 'return' from a recursive call resumes execution at the line immediately following the call.

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