Evaluation of expression Using Stack

Duration: 4 min

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  1. About the Course: About the Course
  2. Section 1 | Language (Hindi): भाषा, लिपि, ध्वनि, वर्ण, अक्षर, स्वर, व्यंजन, मात्रा और संयुक्ताक्षर, वर्तनी, वर्ण-विन्यास, अनुस्वार, अनुनासिक, चंद्रबिंदु और ‘र’ के रूप, शब्द, पद और शब्द-भेद, संज्ञा और सर्वनाम, विशेषण और क्रिया, लिंग, वचन, पुरुष और कारक, काल, वाच्य, वाक्य और वाक्य-भेद, संधि, समास, विलोम शब्द, पर्यायवाची शब्द, सामान्य अशुद्धियाँ, अनेक शब्दों के लिए एक शब्द, मुहावरे और लोकोक्तियाँ, अपठित गद्यांश और अपठित पद्यांश, Multi-Topic Content (Cross-Concept Material), वर्णमाला
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  6. Section 2 | Primary Maths & Reasoning: Ratio and Proportion (Ratios), Divisibility Rules, Mixture and Alligation, Permutation and Combination, Number System, HCF LCM, Sequence and Series (Series), Speed Time and Distance, Series (Number and Letter Series) (Numerical Relations and Reasoning), Coding Decoding, Non Verbal Reasoning (Spatial Aptitude) (Spatial Reasoning) (Visual Reasoning), Percentage, Average, Profit and Loss, Simple Interest and Compound Interest, Time and Work, Mensuration and Geometry, Age Problems, Arithmetic, Powers and Exponents (Surds and Indices), Algebra, Probability, Trigonometry, Syllogisms, Seating Arrangements, Blood Relations, Directions (Direction Test), Analytical Reasoning (Counting Figures Reasoning), Puzzle Solving (Puzzles), Calendar, Clock, Cubes & Dices, Venn Diagram, Data Arrangement, Inequality, Analogy, Ranking, Order and Sequence
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  14. Section 3 | Emerging Trends (AI, Societal Ethics & MS Office): Artificial Intelligence, Emerging Tech Trends, Society, Law & Ethics, MS Office Applications
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  16. Section 3 | C Programming: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling
  17. Section 3 | OOPS, C++, JAVA, HTML: OOPS with C++, Java, HTML Basics, CSS
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  19. Section 3 | Python: Introduction to Python, Tokens, Variables, Data Types, I/O, Operators & Expressions, Control Flow & Looping, Collections & Strings, Functions & Modules, File Handling & Data Analysis
  20. Section 3 | Digital Electronics: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Combinational Circuit, Sequential Circuits, Number System, Number Representation
  21. Section 3 | Multimedia: Multimedia
  22. BPSC Previous Year Papers:
  23. BPSC Full Mock Tests:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

The video lecture focuses on the application of stacks in computer science, specifically for evaluating arithmetic expressions in postfix notation. The instructor, Sanchit Jain Sir from Knowledge Gate, presents a specific problem from the GATE 2015 exam. The problem asks to evaluate the postfix expression `10 5 + 60 6 / * 8 -`. The solution involves using a stack to store operands and performing operations as operators are encountered. The instructor systematically walks through the expression, pushing numbers onto the stack and performing calculations when an operator appears, ultimately arriving at the correct answer among the provided choices.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The video begins with a title slide indicating a 'Break' and the topic 'Application of Stack: Arithmetic Expression Evaluation'. The instructor introduces a GATE 2015 question asking for the result of the postfix expression `10 5 + 60 6 / * 8 -`, with options (A) 284, (B) 213, (C) 142, and (D) 71. He writes the expression on the board and begins the evaluation process. He draws a stack diagram and pushes the first two operands, 10 and 5. Upon encountering the `+` operator, he pops 5 and 10, calculates their sum (15), and pushes the result back onto the stack. Next, he pushes the operands 60 and 6. When the `/` operator is encountered, he pops 6 and 60, performs the division (60 divided by 6 equals 10), and pushes the result 10 onto the stack. At this point, the stack contains 15 and 10, ready for the next operation.

  2. 2:00 – 4:27 02:00-04:27

    Continuing from the previous state, the instructor encounters the `*` operator. He pops the top two elements, 10 and 15, and multiplies them (15 * 10 = 150), pushing the result 150 back onto the stack. He then pushes the next operand, 8, onto the stack. Finally, he encounters the `-` operator. He pops 8 and 150, subtracting 8 from 150 to get the final result of 142. The instructor marks option (C) 142 as the correct answer, completing the step-by-step demonstration of postfix expression evaluation using a stack. He emphasizes the visual representation of the stack growing and shrinking as operations are performed.

This lecture segment effectively demonstrates the practical application of the stack data structure in parsing and evaluating mathematical expressions. By breaking down the GATE 2015 problem, the instructor illustrates the Last-In-First-Out (LIFO) nature of stacks, where operands are stored until an operator triggers a calculation. The example emphasizes the correct order of operands for non-commutative operations like subtraction and division, ensuring students understand how postfix notation simplifies expression evaluation without parentheses. The visual board work reinforces the abstract concept of stack operations.

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