Stack recursion Practice questions

Duration: 3 min

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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 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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