PRACTICE QUESTION STRINGS

Duration: 2 min

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Inside: a video lesson and guided study material.

Module outline

  1. About Course: About the Course
  2. General Aptitude & Reasoning: Number System, Percentage, Ratio and Proportion (Ratios), Average, Profit and Loss, Simple Interest and Compound Interest, Time and Work, Speed Time and Distance, Mixture and Alligation, Data Interpretation, Algebra, Probability, Permutation and Combination, Venn Diagram, HCF LCM, Divisibility Rules, Age Problems, Pipe and Cistern, Partnership, Linear Algebra, Sequence and Series (Series), Statistics, Powers and Exponents (Surds and Indices), Arithmetic, Mensuration and Geometry, Calculus, Trigonometry, Vectors, Speed Mathematics and Basic Mathematics, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Analogy, Series (Number and Letter Series) (Numerical Relations and Reasoning), Puzzle Solving (Puzzles), Syllogisms, Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Calendar, Seating Arrangements, Coding Decoding, Blood Relations, Directions (Direction Test), Clock, Analytical Reasoning (Counting Figures Reasoning), Ranking, Order and Sequence, Logical Sequence Of Words, Inequality, Data Sufficiency, Cubes & Dices
  3. Computer Networks & Cybersecurity: 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 Security
  4. Programming, Data Structures & Algorithms: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling, OOPS with C++, Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing, Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos, Advanced Algorithms
  5. AI, Machine Learning, Big Data & Cloud: Emerging Tech Trends, Artificial Intelligence, Big Data Systems, Approaches to AI, Search Algorithms, Knowledge Representation, Cloud Computing
  6. Digital Logic & Computer Organization: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Number System, Number Representation, Basics of COA, Floating Point Rep, Cache Memory Organization, Input Output Organisation, Pipelining, Instr Formats & Modes, Register Transfer and Microoperations, Control Unit Design, Programming the Basic Computer
  7. TOC & Compiler: Introduction to TOC, Deterministic FA (DFA), Non-Deterministic FA, Regular Expressions, Grammar, Regular Language Properties, Moore & Mealy Machines, Pushdown Automata & CFG, Turing Machines, Complexity Theory, 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
  8. Discrete Mathematics: Set Theory, Relations, Functions, Graph Theory, Group Theory, Propositional and Predicate Logic
  9. 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, Distributed Systems
  10. Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management, Object Oriented Technology, HTML Basics, JavaScript-Basics, Java, XML
  11. Database Management System: 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, Database Recovery, Data Warehousing & Mining, Enhanced Data Models, NoSQL
  12. Other Recurring CS Topics: Basics of Computer Graphics, 2-D Geometrical Transforms and Viewing, Multimedia
  13. Live Classes: ISRO Live classes
  14. Full Mock Test:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

The video features a lecture solving a multiple-choice question regarding the number of substrings of all lengths for a character string of length n. The question displays four options: a) n!, b) n^2, c) n(n-1)/2 - 1, and d) n(n+1)/2 + 1. The instructor highlights the phrase "substrings (of all lengths inclusive)" to clarify the problem scope. He uses the string "GATE" as a concrete example, noting its length is n=4. He systematically lists the substrings: single characters (G, A, T, E), pairs (GA, AT, TE), triplets (GAT, ATE), and the full string (GATE). He counts these to arrive at a total of 11. He then substitutes n=4 into the formulas for options (c) and (d). Option (c) results in 5, while option (d) results in 11. Since his manual count matches option (d), he selects it as the correct answer.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor begins by reading the question: "The number of substrings (of all lengths inclusive) that can be formed from a character string of length n is". He uses a red pen to circle the key terms "substrings" and "of all lengths inclusive" on the screen. To solve this, he writes the example string "GATE" on the digital whiteboard. He breaks down the substrings of "GATE" into groups based on their length: length 1 includes G, A, T, E; length 2 includes GA, AT, TE; length 3 includes GAT, ATE; and length 4 is GATE. He writes "n=4" to denote the length of the example string. He then proceeds to evaluate the given options by substituting n=4. He calculates the value for option (c) n(n-1)/2 - 1, writing "4(3)/2 - 1" which equals 5. He circles the result "5". Next, he evaluates option (d) n(n+1)/2 + 1, writing "4(5)/2 + 1" which equals 11. He writes "11" next to his list of substrings, indicating that he has counted 11 substrings in total.

  2. 2:00 – 2:09 02:00-02:09

    The instructor concludes the problem by finalizing his selection. He has circled the number "11" which corresponds to his manual count of substrings for the string "GATE". He then circles option (d) n(n+1)/2 + 1, confirming it as the correct formula based on the example. The final frame shows the circled option (d) and the calculated value 11, solidifying the connection between the example count and the algebraic expression.

The instructor demonstrates a problem-solving strategy for combinatorial string problems by using a concrete example to verify general formulas. By breaking down the string "GATE" into its constituent substrings and counting them to get 11, he establishes a baseline. He then validates this count against the provided algebraic options, finding that option (d) yields the same value (11) when n=4. This confirms option (d) as the correct answer in the context of this specific problem instance.

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