Practice Question (Gate 1994)

Duration: 3 min

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Module outline

  1. About Course: About the Course
  2. 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
  3. Paper 2 | Computer Organization And Architecture: Basics of COA, Cache Memory Organization, Input Output Organisation, Pipelining, Control Unit Design, Instr Formats & Modes, Programming the Basic Computer
  4. Paper 2 | Analog And Digital Communication: Introduction to Communication Systems & Random Signals, Analog Communication Systems, Information Theory & Digital Communication Fundamentals, Digital Modulation & Detection Techniques, Error Control, Synchronization & Multiple Access Techniques
  5. Paper 2 | Programming in C: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling
  6. Paper 2 | Data Structures And Programming: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing, Java, OOPS with C++, Java Fundamentals, Array, String, IO & References
  7. Paper 2 | Algorithms: Algorithm Analysis, Sorting Algorithms, Time Complexity Analysis, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos
  8. 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
  9. 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, Unix OS, Linux OS
  10. Paper 2 | Databases: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, Relational Algebra, SQL, Relational Calculus, File Organization & Indexing, Transaction Management, Concurrency Control
  11. Paper 2 | Information Systems and Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management
  12. Paper 2 | Computer Networks: 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
  13. Paper 2 | Internet & Web Technologies: Website, Browser & Services, Internet Fundamentals, Web Design & Development, Protocols & Services, Web Publishing & Hosting, Server Side & Security, Emerging Technologies, HTML Basics, JavaScript-Basics, CSS, XML, HTML5
  14. Paper 2 | Cyber Security And Emerging Technologies: Emerging Tech Trends
  15. Paper 2 | Cloud Technology: Cloud Computing
  16. Paper 2 | Probability and statistics: Probability, Statistics
  17. Paper-1 English: Vocabulary, Preposition, Articles, 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), Cloze Test (Cloze Passage), Sentence Construction
  18. Paper 1 General Mental Ability & Logical reasoning: Ratio and Proportion (Ratios), Divisibility Rules, Data Interpretation, Mixture and Alligation, Permutation and Combination, Logarithm, Number System, HCF LCM, Sequence and Series (Series), Speed Time and Distance, Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Data Sufficiency, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Percentage, Average, Powers and Exponents (Surds and Indices), Algebra, Profit and Loss, Simple Interest and Compound Interest, Time and Work, Pipe and Cistern, Mensuration and Geometry, Mental Ability, Age Problems, Partnership, Arithmetic, Speed Mathematics and Basic Mathematics, Syllogisms, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Seating Arrangements, Blood Relations, Directions (Direction Test), Analytical Reasoning (Counting Figures Reasoning), Puzzle Solving (Puzzles), Calendar, Clock, Cubes & Dices, Selection Decision Table (Decision Making), Logical Sequence Of Words, Venn Diagram, Analogy
  19. Paper-1 General Knowledge & Current Affairs: State Wise GK, History, Geography, GK- Current Affairs, Static General Knowledge
  20. Full Length Mock Test:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

The video features a lecture on data structures, specifically focusing on a GATE 1994 problem about stack permutations. The problem asks which of the given output sequences can be generated from the input sequence 1, 2, 3, 4, 5 using a single stack. The instructor systematically evaluates four options: (a) 3, 4, 5, 1, 2; (b) 3, 4, 5, 2, 1; (c) 1, 5, 2, 3, 4; and (d) 5, 4, 3, 1, 2. He uses a visual representation of a stack to trace the necessary push and pop operations for each case, demonstrating the Last In First Out (LIFO) property.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor starts by reading the question and drawing a stack diagram. He analyzes option (a) 3, 4, 5, 1, 2. To output 3, he pushes 1, 2, 3 and pops 3. To output 4, he pushes 4 and pops 4. To output 5, he pushes 5 and pops 5. At this point, the stack contains 1 and 2, with 2 at the top. Since the next required output is 1, but 2 is blocking it, he marks option (a) as incorrect. He then analyzes option (b) 3, 4, 5, 2, 1. He performs the same pushes for 3, 4, and 5. After popping 5, the stack has 1 and 2. He pops 2, then pops 1, successfully matching the sequence. He marks option (b) as correct. He briefly checks option (c) 1, 5, 2, 3, 4, showing that after popping 5, the stack has 2, 3, 4, making it impossible to pop 2 next.

  2. 2:00 – 2:35 02:00-02:35

    The instructor concludes the analysis by checking option (d) 5, 4, 3, 1, 2. He pushes 1 through 5, pops 5, 4, 3. The stack now contains 1 and 2. The next required output is 1, but 2 is on top. He crosses out option (d). He confirms that option (b) is the only valid permutation. He reiterates the core concept that a stack follows the Last In First Out (LIFO) principle, meaning elements must be popped in reverse order of their insertion if they are waiting in the stack.

The lecture effectively demonstrates how to validate stack permutations by simulating the push and pop operations. The key takeaway is that for any valid stack permutation, if an element is pushed onto the stack, it must be popped before any elements pushed after it can be popped. This LIFO constraint is the primary filter used to eliminate invalid options like (a), (c), and (d), leaving (b) as the correct answer.

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