Practice Set 7 (Recursion, Function) Q16-20

Duration: 8 min

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Inside: a video lesson and guided study material.

Module outline

  1. About Course: About the Course
  2. Section A: General Awareness: Polity, Physics, Biology, Chemistry, Static General Knowledge, History, Geography, Indian Economy, GK- Current Affairs, Evolution of Indian Banking (Banking & Financial Awareness), Environment
  3. Section A: General Intelligence & Reasoning ability: Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Data Sufficiency, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Analytical Reasoning (Counting Figures Reasoning), Blood Relations, Syllogisms, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Seating Arrangements, Directions (Direction Test), Puzzle Solving (Puzzles), Calendar, Clock, Cubes & Dices, Selection Decision Table (Decision Making), Logical Sequence Of Words, Crypt Arithmetic, Venn Diagram, Data Arrangement, Inequality, Analogy, Ranking, Order and Sequence, TCS NQT Advanced Reasoning Ability
  4. Section A: Arithmetical & Numerical Ability: 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, Percentage, Average, Profit and Loss, Simple Interest and Compound Interest, Time and Work, Pipe and Cistern, Mensuration and Geometry, Powers and Exponents (Surds and Indices), Algebra, Probability, Mental Ability, Age Problems, Partnership, Statistics, Arithmetic, Speed Mathematics and Basic Mathematics, Miscellaneous
  5. Section A: English Language & Comprehension: Vocabulary, Subject Verb Agreement (Verb Noun Agreement), Adjectives, Tenses, Comprehension / Reading Comprehension / Unseen Passages (Critical Reasoning) (Paragraph Questions), Articles, Sentence Construction, Preposition, Direct and Indirect Speech, Sentence Completion (Fill in the blanks), Sentence Re-arrangements (Para Jumbles) (Narrative Sequencing), Modals, Active Passive Voice (Voice), Sentence Correction (Error Correction), Adverb, Conjunction, Cloze Test (Cloze Passage)
  6. Section A: Hindi Language & Comprehension: भाषा, लिपि, ध्वनि, वर्ण, अक्षर, स्वर, व्यंजन, मात्रा और संयुक्ताक्षर, वर्तनी, वर्ण-विन्यास, अनुस्वार, अनुनासिक, चंद्रबिंदु और ‘र’ के रूप, शब्द, पद और शब्द-भेद, संज्ञा और सर्वनाम, विशेषण और क्रिया, लिंग, वचन, पुरुष और कारक, काल, वाच्य, वाक्य और वाक्य-भेद, संधि, समास, विलोम शब्द, पर्यायवाची शब्द, सामान्य अशुद्धियाँ, अनेक शब्दों के लिए एक शब्द, मुहावरे और लोकोक्तियाँ, अपठित गद्यांश और अपठित पद्यांश, Multi-Topic Content (Cross-Concept Material), वर्णमाला
  7. Section B: Programming, Data Structures, OOP & Java: 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, Java, OOPS with C++, Language Design, Intro to Compilers, Visual Basics, Syntax Analysis: Bottom-Up, Object Oriented Technology
  8. Section B: Computer Networks, TCP/IP & Network Security: Introduction to CN, Data Communication, DLL: Flow Control, DLL: Access Control, DLL: Error Control, Data Link Layer - Ethernet, Net Layer: IPv4 & Proto, Net Layer: IP Addressing, Transport Layer Services, TL: Congestion & UDP, Application Layer, Hardware basics, Network Access Technologies, Network Security, Society, Law & Ethics, Mobile Computing, Net Layer:Routing Protocol, Cyber Safety and Security
  9. Section B: Teaching Methodology: Child Development, Concept of Pedagogy, Theories, Inclusive Education, Experiential Pedagogy, Assessment & Evaluation, Curriculum Framework & Reforms, National Education Policy (NEP) 2020, Psychology, Teaching-Learning Process, Personality Development, Teaching Methods & Strategies, Learning and Motivation, Learners & Learning Process, Factors Affecting Teaching, Methods of Teaching, Nature, Objectives & Characteristics of Teaching, Teaching-Learning Aids & ICT Integration, Classroom Management & Communication, Evaluation, Assessment & Measurement, Curriculum & School Environment, Inclusive Education & Special Needs, Professional Development & Ethics
  10. Section B: Digital Electronics / Boolean Logic: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Number System, Number Representation, Analog-Digital Conversion
  11. Section B: Operating Systems & Linux: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Threads & Process Creation, Deadlock, Memory Management, Virtual Memory, File Management, Disc Scheduling, Unix OS, Linux OS, Distributed Systems, Windows OS
  12. Section B: Data Base Management System: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, Relational Algebra, SQL, File Organization & Indexing, Transaction Management, Concurrency Control, Database Security & Authorization, Database Recovery, Data Warehousing & Mining
  13. Section B: Internet & Web Technologies: Website, Browser & Services, Internet Fundamentals, Web Design & Development, Protocols & Services, Web Publishing & Hosting, Server Side & Security, HTML Basics, CSS, Emerging Technologies, JavaScript-Basics, .Net Programming, Electronic Data Interchange and E-Commerce, XML
  14. Section B: Computer Fundamentals, IT Basics & Architecture: Basics of COA, Cache Memory Organization, Input Output Organisation, Register Transfer and Microoperations, Control Unit Design, Programming the Basic Computer, Terms & Abbreviations, MS Office Applications, Instr Formats & Modes, Floating Point Rep
  15. Section B: Python Language: Introduction to Python, Tokens, Variables, Data Types, I/O, Operators & Expressions, Control Flow & Looping, Collections & Strings, Functions & Modules, File Handling & Data Analysis
  16. Section B: Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management, extras, Fundamentals of Systems and Information Systems
  17. Section B: Design & Analysis of Algorithms: Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos, Advanced Algorithms
  18. Section B: Mathematics: Linear Algebra, Calculus, Trigonometry, Vectors, Set Theory, Functions, Relations, Propositional and Predicate Logic, Research Process Steps, Graph Theory
  19. Section B: Computer Graphics, Multimedia & Mobile Computing: Basics of Computer Graphics, 2-D Geometrical Transforms and Viewing, 3-D Object Representation, Geometric Transformations and Viewing, Multimedia
  20. Section B: Emerging Trends: Emerging Tech Trends, Knowledge Representation, Natural Language Processing
  21. DSSSB Previous Year Paper:
  22. Business Studies and Management: Business Communication, Business Organization and Management, Financial Accounting, Business Economics, Management Information System (MIS), Knowledge Management & New Economy
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This video is a lecture on Python programming, focusing on solving a series of practice questions from a document titled 'Python Practice Question Sheet.pdf'. The instructor, a man in a dark blue shirt, uses a digital whiteboard to explain the logic and execution of various Python functions. The session begins with Question 16, which involves a recursive function to calculate the factorial of 6, with the instructor demonstrating the step-by-step recursion process. The video then transitions to Question 17, where the instructor analyzes a function that uses the `isinstance` function to check if an argument is a set, and then calls `len` on it. The final segment covers Question 18 and Question 20, both of which involve recursive functions that manipulate lists. For Question 18, the function `f(n)` returns a list of numbers from n down to 1. For Question 20, the function `f(l, n)` recursively builds a list by taking the first element of the list `l` and appending the result of a recursive call with the rest of the list and a decremented `n`. The instructor uses on-screen diagrams and handwritten calculations to illustrate the recursive calls and their return values, providing a clear, step-by-step walkthrough of each problem.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The video starts with Question 16, which presents a recursive function `f(n)` defined as `return 1 if n==0 else n * f(n-1)`. The instructor explains that this is a factorial function and proceeds to calculate `f(6)`. He writes out the recursive expansion on the board: `6 * f(5)`, `5 * f(4)`, and so on, down to `1 * f(0)`. He then calculates the final result as `6 * 5 * 4 * 3 * 2 * 1 = 720`. The on-screen text clearly shows the function definition and the question `print(f(6))`. The instructor uses a yellow marker to draw arrows and write the calculation steps, visually demonstrating the recursion process.

  2. 2:00 – 5:00 02:00-05:00

    The instructor moves to Question 17, which defines a function `f(x)` that checks if `x` is an instance of a set using `isinstance(x, set)`. If true, it returns the length of `x`. The function is then called with `f([1,2,3])`. The instructor explains that a list is not a set, so the condition `isinstance([1,2,3], set)` is false. The function then calls `f(set(x))`, which converts the list to a set `{1,2,3}`. The function is called again with this set, and since `isinstance({1,2,3}, set)` is true, it returns `len({1,2,3})`, which is 3. The instructor writes `f([1,2,3])` and then `f(set([1,2,3]))` on the board, showing the transformation. The on-screen text shows the function definition and the print statement `print(f([1,2,3]))`. The instructor concludes that the output is 3, which corresponds to option (a).

  3. 5:00 – 7:47 05:00-07:47

    The video transitions to Question 18, which defines a function `f(n)` that returns a list. The function returns `[n] + f(n-2)` if `n > 0`, and returns an empty list `[]` if `n == 0`. The instructor demonstrates the recursion for `f(7)`. He writes `f(7)` and then `f(7) = [7] + f(5)`. He continues this process, writing `f(5) = [5] + f(3)`, `f(3) = [3] + f(1)`, and `f(1) = [1] + f(-1)`. Since `n = -1` is not greater than 0, `f(-1)` returns `[]`. The final result is `[7,5,3,1]`. The on-screen text shows the function and the print statement `print(f(7))`. The instructor then moves to Question 20, which defines a function `f(l, n)` that returns a list. The function returns `l[0] + f(l[1:], n-1)` if `n > 0`, and returns `[]` if `n == 0`. The instructor demonstrates `f([1,2,3,4], 2)`. He writes `f([1,2,3,4], 2) = [1] + f([2,3,4], 1)`. Then `f([2,3,4], 1) = [2] + f([3,4], 0)`. Since `n == 0`, `f([3,4], 0)` returns `[]`. The final result is `[1,2]`. The on-screen text shows the function and the print statement `print(f([1,2,3,4], 2))`. The instructor uses the board to draw the recursive calls and their results.

The video provides a comprehensive walkthrough of several Python programming problems, emphasizing the core concept of recursion. The instructor systematically breaks down each question, starting with a clear explanation of the function's logic, followed by a step-by-step trace of the recursive calls. The use of a digital whiteboard to visually map out the recursion tree and calculate intermediate values is a key teaching method. The problems cover different aspects of recursion: calculating a mathematical function (factorial), manipulating data types (converting a list to a set), and building a list from a sequence. The progression from simple mathematical recursion to more complex list manipulation demonstrates a well-structured learning path, helping students understand how to approach and solve recursive problems in Python.

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