Substring

Duration: 7 min

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Inside: a video lesson and guided study material.

Module outline

  1. About Course: About the Course
  2. English Language: Vocabulary, Noun, Adjectives, Tenses, Pronoun, Adverb, Preposition, Conjunction, Active Passive Voice (Voice), Articles, Direct and Indirect Speech, Sentence Correction (Error Correction), Sentence Re-arrangements (Para Jumbles) (Narrative Sequencing), Comprehension / Reading Comprehension / Unseen Passages (Critical Reasoning) (Paragraph Questions), Sentence Completion (Fill in the blanks), Cloze Test (Cloze Passage)
  3. Reasoning: Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Data Sufficiency, Puzzle Solving (Puzzles), Seating Arrangements, Blood Relations, Syllogisms, Inequality, Directions (Direction Test), Deductive and Inductive Reasoning (Logical Deduction and Induction) (Prepositional Reasoning), Clock, Calendar, Analytical Reasoning (Counting Figures Reasoning), Selection Decision Table (Decision Making), Cubes & Dices, Machine Input-Output
  4. Quantitative Aptitude: Ratio and Proportion (Ratios), Data Interpretation, Mixture and Alligation, Permutation and Combination, Number System, Sequence and Series (Series), Speed Time and Distance, Algebra, Speed Mathematics and Basic Mathematics, Percentage, Average, Time and Work, Simple Interest and Compound Interest, Profit and Loss, Age Problems, Partnership, Mensuration and Geometry, Probability, IBPS Specific Videos
  5. Data Structures - Professional Knowledge: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing
  6. Algorithms- Professional Knowledge: Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Dynamic Programming, Minimum Spanning Trees, Shortest Path Algos
  7. Python- Professional Knowledge: Python for Placements by Yash Sir, Python Basics
  8. Operating System- Professional Knowledge: Introduction to OS, Process Management, CPU Scheduling, Deadlock, Threads & Process Creation, Memory Management, Virtual Memory, Disc Scheduling, File Management
  9. DBMS + SQL- Professional Knowledge: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), File Organization & Indexing, SQL, Transaction Management, Concurrency Control
  10. Computer Networks- Professional Knowledge: Introduction to CN, Data Communication, Net Layer: IP Addressing, Net Layer: IPv4 & Proto, Application Layer, Hardware basics, Network Security
  11. Software Engineering- Professional Knowledge: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management
  12. Computer Organization & Microprocessor- Professional Knowledge: Basics of COA, Cache Memory Organization, Programming the Basic Computer
  13. Digital Logic Design- Professional Knowledge: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Number System, Number Representation
  14. Theory of Computation- Professional Knowledge: Introduction to TOC, Deterministic FA (DFA), Non-Deterministic FA, Regular Expressions, Regular Language Properties, Pushdown Automata & CFG, Turing Machines
  15. Compiler Design- Professional Knowledge: Intro to Compilers, Lexical Analysis, Grammar & CFG, Syntax Analysis: Top-Down, Intermediate Code Gen, Code Optimization
  16. Programming Languages- Professional Knowledge: C Programming by Yash Sir, Object Oriented Programming (OOPS), Programming in C++, Java, C Language Core
  17. Emerging Tech- Professional Knowledge: Emerging Tech Trends
  18. Artificial Intelligence: Artificial Intelligence
  19. Unit Test - Professional Knowledge:
  20. Full Length Mock Test:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

The video lecture defines the concept of a substring as a sequence of consecutive symbols within a larger string. The instructor uses the word 'SUBSTRING' to demonstrate valid examples like 'str' and 'sub' versus invalid non-consecutive sequences. He then transitions to calculating the total number of substrings for a specific string, 'GATE', using a tabular method to count substrings by length. This leads to the derivation of a general formula, n(n+1)/2 + 1. Finally, the lecture distinguishes between trivial and non-trivial substrings, providing a formula to calculate the latter by excluding the empty string and the string itself.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor begins by defining a substring with on-screen text: 'Substring- Any string of consecutive symbols in some string 'w' can be collectively said as a substring.' He gives an example 'w= abab' where substrings include 'ab', 'a', 'ba'. He then presents the string 'S u b s t r i n g' and a numbered list of potential substrings: 1. utg, 2. sbr, 3. rts, 4. str, 5. sub, 6. $\epsilon$. He marks items 1, 2, and 3 with red crosses, explaining they are not consecutive. He marks 4 ('str'), 5 ('sub'), and 6 ($\epsilon$) with checkmarks, confirming they are valid substrings because the characters appear consecutively in the original string.

  2. 2:00 – 5:00 02:00-05:00

    The lecture shifts to a problem: 'Consider a string 'GATE' find the total number of substring possible?'. A table is displayed with columns for substring lengths 0 through 4. The instructor fills the table row by row. For length 0, he writes $\epsilon$ (1 substring). For length 1, he lists G, A, T, E (4 substrings). For length 2, he lists GA, AT, TE (3 substrings). For length 3, he lists GAT, ATE (2 substrings). For length 4, he lists GATE (1 substring). He sums these values: 1 + 4 + 3 + 2 + 1 = 11. He writes the formula for this sum on the board: n(n+1)/2 + 1, circling the result 11 to emphasize the total count.

  3. 5:00 – 6:44 05:00-06:44

    The instructor briefly considers a string 'GGGE' to test the counting method, filling a similar table with counts 1, 2, 2, 2, 1 and writing a 9 next to the sum. He then moves to a slide defining trivial and non-trivial substrings. The text reads: 'If w is any string than empty string $\epsilon$ and the string w itself is called a trivial substring and the remaining of the other are the non-trivial sub string'. He writes the formula for non-trivial substrings on the board as [n(n+1)/2 + 1] - 2, explaining that this subtracts the empty string and the string itself from the total count.

The lesson progresses from a basic definition of substrings to a quantitative analysis of how many exist in a string. By breaking down the problem into lengths and using a table, the instructor derives a general formula. The distinction between trivial and non-trivial substrings adds a layer of complexity, refining the count by excluding the empty string and the full string itself.

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