Practice Question (Gate 1995)

Duration: 4 min

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Module outline

  1. About Course: BTSC About Course
  2. Basics of Computer Science: Basics of COA, Number System, Number Representation
  3. Operating System: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Threads & Process Creation, Deadlock, Memory Management, Virtual Memory
  4. Data Structures & Algorithms: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing, Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms
  5. Database Management Systems(DBMS): Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Relational Algebra, SQL, Transaction Management, Concurrency Control, Database Recovery
  6. Networking and Internet: Introduction to CN, Data Communication, Net Layer: IPv4 & Proto, Net Layer: IP Addressing, Application Layer, Hardware Basics, Network Access Technologies, Network Security
  7. Cyber Security Basics: Cyber Threats and Malware Attacks, Role of Internet and Web Services, Electronic Data Interchange and E-Commerce, Cyber Safety and Security
  8. C Programming (Programming Fundamentals): C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling
  9. C++, OOPs & Java (Programming Fundamentals): Java, OOPS with C++
  10. Python (Programming Fundamentals): Introduction to Python, Tokens, Variables, Data Types, I/O, Operators & Expressions, Control Flow & Looping, Collections & Strings, Functions & Modules
  11. Web Development Basics: Internet Fundamentals, Web Design & Development, Protocols & Services, Web Publishing & Hosting, Server Side & Security, Emerging Technologies, JavaScript-Basics, HTML Basics
  12. Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing
  13. Software and Hardware Tools: MS Office Applications, Unix OS, Linux OS
  14. Emerging Trends. AI & Social Ethics: Artificial Intelligence, Emerging Tech Trends, Society, Law & Ethics
  15. Full Mock Test:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

This lecture solves a GATE 1995 multiple-choice question asking for the postfix expression of A+B*(C+D)/F+D*E. The instructor writes the infix expression on a whiteboard and converts it step by step, beginning with the innermost parentheses. The subexpression (C+D) is replaced by its postfix form CD+, underlining the operator to track conversion order. The multiplication B*(CD+) is then grouped as BCD+*, and division by F gives BCD+*F/. The remaining addition A + ... and the final D*E term are processed to produce the complete postfix string ABCD+*F/+DE*+. The final answer is underlined at the bottom of the board and matches option (b). The method emphasizes operator precedence, associativity, and incremental replacement of subexpressions with their postfix equivalents.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The video opens with the GATE 1995 question: 'The postfix expression for the infix expression A+B*(C+D)/F+D*E is:' with four options. The instructor writes the full infix expression on the whiteboard, then begins conversion by underlining the + inside (C+D) and rewriting it as CD+. The expression becomes A+B*CD+/F+D*E, showing the first precedence-based simplification.

  2. 2:00 – 3:38 02:00-03:38

    The instructor continues the conversion, grouping B*CD+ as BCD+*, then applying division by F to form BCD+*F/. The remaining A + ... and D*E parts are processed, yielding the final postfix string ABCD+*F/+DE*+, which is underlined at the bottom of the board. This matches option (b), ABCD+*F/DE*++.

The core teaching point is the systematic infix-to-postfix conversion rule: process parentheses first, then apply operator precedence and associativity, replacing each subexpression with its postfix equivalent. The worked example demonstrates that (C+D) becomes CD+, B*(CD+) becomes BCD+*, and the full expression resolves to ABCD+*F/+DE*+. The underlining technique helps students track which operators have been moved. This method is directly applicable to similar GATE questions involving nested parentheses and mixed precedence.

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