Tree Traversal Pseudocode PQ

Duration: 7 min

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Module outline

  1. General Intelligence & Reasoning: Analogy, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Blood Relations, Directions (Direction Test), Ranking, Order and Sequence, Logical Sequence Of Words, Syllogisms, Venn Diagram, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Selection Decision Table (Decision Making), Data Sufficiency, Puzzle Solving (Puzzles), Data Arrangement, Cubes & Dices, Calendar, Clock, Arithmetic, Number System, HCF LCM, Verbal Analogy (Word Based Analogy), Visual Recognition and Figure Completion, Paper Folding and Cutting, Transformation of Shapes, Clocks and Calendars, Direction Sense, Cubes and Dice, Patterns in Two-Dimensional Figures, Seating Arrangements, Analogy and Classification, Logical Deduction and Induction, Alphabet and Word Tests, Mathematical Operations, Series Completion, Simplification and Approximation, Coding and Decoding, Numerical Reasoning, Assembling and Grouping of Shapes, Three-Dimensional Patterns and Visualization, Vocabulary, Number System, Averages, Mixtures and Alligation, Simple and Compound Interest, Percentages, Algebra, Speed, Time and Distance, Seating and Arrangement Puzzles, Traverse Surveying, Order, Ranking and Sequence, Constraint Puzzles, Syllogisms and Venn Diagrams, Reading Comprehension, Critical Reasoning, Permutations and Combinations, Narrative Sequencing, Project Monitoring, Resources and Safety, Profit, Loss and Discount, Ratio and Proportion, Time and Work, Mensuration, Data Interpretation, Powers, Surds and Logarithms, Sequences and Series, Articles and Determiners, Sentence Completion, Data Sufficiency, Blood Relations, Simple Interest and Compound Interest, Mixture and Alligation, Sequence and Series (Series), Speed Time and Distance, Algebra, Profit and Loss, Powers and Exponents (Surds and Indices), Permutation and Combination
  2. General Awareness: Physics, Chemistry, Biology, History, Geography, Polity, Indian Economy, Environment, Static General Knowledge, GK- Current Affairs, Artificial Intelligence, MS Office Applications, Terms & Abbreviations, Keyboard Shortcuts, Evolution of Indian Banking (Banking & Financial Awareness), Emerging Tech Trends
  3. Engineering Mathematics: Set Theory, Relations, Functions, Graph Theory, Group Theory, Propositional and Predicate Logic, Linear Algebra, Calculus, Probability, Statistics, Signal Space and Optimum Detection, Probability, Statistics
  4. Digital Logic: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Number System, Number Representation, Floating Point Rep, Number Systems and Codes, Registers and Counters, Boolean Algebra and Logic Gates, Microprocessors and Microcontrollers, Logic Families and CMOS Logic, Microprocessors, Logic Gates and Boolean Algebra, Minimization of Boolean Functions, Timing, Hazards and Testing, Logic Families, Combinational Logic Design, Arithmetic Circuits, Waveform Generators and Timer Circuits, Semiconductor Memories and Programmable Logic Devices, Combinational Logic Circuits, Latches and Flip-Flops, Finite State Machines, Sequential Circuits and State Machines, Minimization of Boolean Functions, Arithmetic Circuits, Latches and Flip-Flops, Number Systems and Codes, Registers and Counters
  5. Computer Organisation & Architecture: Basics of COA, Cache Memory Organization, Input Output Organisation, Pipelining, Instr Formats & Modes, Control Unit Design, Programming the Basic Computer, Register Transfer and Microoperations, Semiconductor Memories and Programmable Logic, Processor Organization and Instructions, Memory Hierarchy and Input/Output, Registers and Counters
  6. Programming & Data Structures: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling, Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing, HTML Basics, OOPS with C++, Java, Object Oriented Technology
  7. Databases: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, File Organization & Indexing, Relational Algebra, SQL, Relational Calculus, Transaction Management, Concurrency Control, Database Recovery, Database Security & Authorization
  8. Algorithms: Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos
  9. Theory of Computation: Introduction to TOC, Deterministic FA (DFA), Non-Deterministic FA, Regular Expressions, Grammar, Regular Language Properties, Moore & Mealy Machines, Pushdown Automata & CFG, Turing Machines, Complexity Theory
  10. 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
  11. Operating System: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Threads & Process Creation, Deadlock, Memory Management, Virtual Memory, Disc Scheduling, File Management, Security, Windows OS, Distributed Systems, Unix OS, Linux OS
  12. Computer Networks: Introduction to CN, 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, Data Communication, Website, Browser & Services, Web Design & Development, Network Security, Cyber Threats and Malware Attacks, Cyber Safety and Security
  13. Full Length Mock Tests:
  14. Sectional Tests:
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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