Stack recursion Practice questions

Duration: 3 min

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Module outline

  1. About Course: About the Course
  2. Paper-2 | 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
  3. Paper-2 | Databases / DBMS & SQL: 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
  4. Paper-2 | Algorithms: Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos
  5. Paper-2 | Computer Networks & Security: 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, Network Access Technologies, Network Security
  6. 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
  7. 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
  8. Paper-2 | 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
  9. Paper-2 | Computer Organization & Architecture: Basics of COA, Cache Memory Organization, Input Output Organisation, Pipelining, Instr Formats & Modes, Control Unit Design, Programming the Basic Computer
  10. 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
  11. Paper-1 | General Awareness: Polity, Physics, Biology, Chemistry, Static General Knowledge, GK- Current Affairs, History, Geography, Indian Economy, Environment
  12. Paper-1 | Logical Reasoning: Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Data Interpretation, Blood Relations, Syllogisms, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Selection Decision Table (Decision Making), Clock, Calendar, Cubes & Dices, Directions (Direction Test), Analogy, Seating Arrangements, Analytical Reasoning (Counting Figures Reasoning)
  13. Paper-1 | Quantitative Aptitude: Ratio and Proportion (Ratios), Mixture and Alligation, Permutation and Combination, Number System, HCF LCM, Speed Time and Distance, Average, Age Problems, Percentage, Profit and Loss, Time and Work, Pipe and Cistern, Simple Interest and Compound Interest, Powers and Exponents (Surds and Indices), Mensuration and Geometry, Probability, Statistics, Arithmetic, Algebra
  14. Paper-1 | English: Vocabulary, 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), Sentence Construction, Cloze Test (Cloze Passage)
  15. Coal India Previous Year Paper:
  16. Engineering Mathematics: Set Theory, Relations, Functions, Graph Theory, Group Theory, Propositional and Predicate Logic, Linear Algebra, Calculus
  17. Coal India Mock Test:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

The video presents a computer science problem asking to identify the functionality of a given recursive C function. The function fun(int x, int y) takes two integer arguments. The instructor analyzes the code structure, identifying a base case where y equals 0 returns 0, and a recursive step that adds x to the result of fun(x, y-1). To understand the behavior, the instructor sets up a concrete example with x = 2 and y = 4. He manually traces the recursion, expanding the function calls step-by-step until the base case is reached. After calculating the final result, he evaluates four multiple-choice options to find the mathematical equivalent of the function's operation.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The segment begins with the problem statement and code display. The instructor underlines the condition if (y == 0) and the return statement return 0. He then introduces test values x = 2 and y = 4 to trace the execution. He writes fun(2, 4) on the board and begins expanding the recursive calls. The expansion shows Return (2 + fun(2, 3)), followed by Return (2 + fun(2, 2)), and Return (2 + fun(2, 1)). The tracing continues until the base case Return (2 + fun(2, 0)) is reached. The instructor underlines y == 0 to emphasize the stopping condition. He then starts the backtracking process, calculating 2 + 0 = 2 for the base case return value. This section establishes the recursive structure and begins the manual execution trace.

  2. 2:00 – 3:24 02:00-03:24

    The instructor continues the backtracking calculation from the previous window. He computes the return values for each recursive level: fun(2, 1) returns 2, fun(2, 2) returns 4, fun(2, 3) returns 6, and finally fun(2, 4) returns 8. With the result 8 established, he systematically checks the provided options. He calculates x + y as 6, x + x*y as 10, x*y as 8, and x^y as 16. He marks option (A) and (B) as incorrect. He identifies that option (C) x*y matches the calculated result of 8. He places a checkmark next to option (C) and crosses out the others, confirming that the function performs multiplication. The video concludes with the correct answer identified.

The lecture effectively demonstrates a standard technique for analyzing recursive algorithms: manual tracing with concrete inputs. By substituting specific values, the abstract recursion becomes a concrete arithmetic sequence. The instructor shows that adding x repeatedly y times is mathematically equivalent to multiplying x by y. This method of tracing execution flow and comparing results against options is a crucial skill for solving recursion problems in computer science exams. It highlights the importance of understanding base cases and recursive steps in algorithm design.

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