Stack Practice questions

Duration: 10 min

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Inside: a video lesson and guided study material.

Module outline

  1. HPSC Interview Preparation: Interview Preparation
  2. Python Language: Introduction to Python, Tokens, Variables, Data Types, I/O, Operators & Expressions, Control Flow & Looping, Collections & Strings, Functions & Modules, File Handling & Data Analysis, DSA using Python
  3. Data Structure & Algorithms: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing, Algorithm Analysis, Sorting Algorithms, Minimum Spanning Trees, Time Complexity Analysis, Graph Theory, Shortest Path Algos
  4. Computer Networks: Introduction to CN, Data Communication, DLL: Access Control, DLL: Flow Control, Data Link Layer - Ethernet, Net Layer: IPv4 & Proto, Net Layer: IP Addressing, Transport Layer Services, TL: Congestion & UDP, Application Layer, Hardware basics, Network Security
  5. Computer System & Organisation: Basics of COA, Cache Memory Organization, Input Output Organisation, Pipelining, Instr Formats & Modes, Control Unit Design, Programming the Basic Computer
  6. Database Management System: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, SQL, File Organization & Indexing, Transaction Management, Concurrency Control
  7. Operating Systems: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Deadlock, Threads & Process Creation, Memory Management, Virtual Memory, Disc Scheduling
  8. Digital Logic & Circuits: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Number System, Number Representation
  9. Theory Of Computation: Introduction to TOC, Deterministic FA (DFA), Non-Deterministic FA, Regular Expressions, Grammar, Regular Language Properties, Pushdown Automata & CFG, Turing Machines, Moore & Mealy Machines
  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. Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management, Data Warehousing & Mining
  12. Introduction to Emerging Trends: Emerging Tech Trends
  13. Digital Society & Cyber Law: Society, Law & Ethics
  14. HPSC PGT Previous Year Paper:
  15. HPSC Assistant Professor Previous Year Paper:
  16. Live Sessions: HPSC Live Sessions, EMRS TGT/PGT Live Class
  17. Full Mock Test:
  18. HPSC PGT - MOCK Test Series:
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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