Stack Practice questions

Duration: 10 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 lecture analyzes two C functions, `fun` and `fun2`, to determine the mathematical operation performed by `fun2`. The instructor first identifies that `fun(x, y)` implements multiplication (`x * y`). He then traces the execution of `fun2(a, b)` using specific inputs (a=2, b=3) to find the output. By expanding the recursive calls, he calculates the result as 8. Finally, he generalizes the recursive structure of `fun2` to show that it computes `a` raised to the power of `b` (exponentiation), confirming option (C) as the correct answer.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor introduces the problem by displaying two C functions on the screen: `fun(int x, int y)` and `fun2(int a, int b)`. He begins by analyzing `fun`, noting that it recursively adds `x` to itself `y` times, effectively implementing multiplication (`x * y`). He then sets up a trace for `fun2` using the specific input values `a=2` and `b=3`. He writes down the initial recursive expansion on the whiteboard: `fun2(2, 3)` calls `fun(2, fun2(2, 2))`. He continues to expand the inner call, writing `fun(2, fun(2, fun2(2, 1)))` and then `fun(2, fun(2, fun(2, fun2(2, 0))))`. This establishes the recursive structure needed to evaluate the function.

  2. 2:00 – 5:00 02:00-05:00

    The instructor proceeds to evaluate the nested function calls starting from the base case. He identifies that `fun2(2, 0)` returns `1` based on the base condition `if (b == 0) return 1;`. Substituting this back, the expression becomes `fun(2, fun(2, fun(2, 1)))`. He evaluates the innermost `fun(2, 1)` as `2 * 1 = 2`. The expression simplifies to `fun(2, fun(2, 2))`. Next, he evaluates `fun(2, 2)` as `2 * 2 = 4`. The expression further simplifies to `fun(2, 4)`. Finally, he calculates `fun(2, 4)` as `2 * 4 = 8`. He writes `2^3 = 8` on the board, noting that the result matches the power operation.

  3. 5:00 – 9:52 05:00-09:52

    To confirm the general behavior, the instructor analyzes the recursive step of `fun2` algebraically. He observes that `fun2(a, b)` returns `fun(a, fun2(a, b-1))`. Since `fun(x, y)` is multiplication, this translates to `a * fun2(a, b-1)`. This recurrence relation, `f(a, b) = a * f(a, b-1)` with base case `f(a, 0) = 1`, is the standard definition of exponentiation `a^b`. He compares this with the given options: (A) `a*b`, (B) `a+a*b`, (C) `a^b`, and (D) `b^a`. Although option (B) also yields 8 for inputs (2,3), the recursive structure `a * fun2(...)` clearly matches exponentiation, not addition. He circles option (C) `a^b` as the correct answer, concluding that `fun2` computes `a` raised to the power of `b`.

The lecture demonstrates a method for analyzing recursive C functions by first simplifying helper functions and then tracing specific examples to find a pattern. By identifying `fun` as multiplication and tracing `fun2(2, 3)` to get 8, the instructor establishes a numerical pattern. He then generalizes the recursive step `fun(a, fun2(a, b-1))` into the algebraic form `a * fun2(a, b-1)`, which definitively proves that `fun2` implements exponentiation `a^b`.

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