Stacks & Queues in list

  • Question 1
    CBSEENCO12011593

    Evaluate the following Postfix notation of expression:
    4,2,*,22,5,6,+,/,-

    Solution
    Element Stack Contents  
    4 4
    2 4,2
    * 8
    22 8, 22
    5 8, 22, 5
    6 8, 22, 5, 6
    + 8, 22, 11
    / 8, 2
    - 6
    Question 2
    CBSEENCO12011594

    Differentiate between file modes r+ and rb+ with respect to Python.

    Solution

    Difference b/w r+ and rb+ with respect to Python

    r+   rb+ 
    r+ Opens a file for both reading and writing. The file pointer placed at the beginning of the file. rb+ Opens a file for both reading and writing in binary format. The file pointer placed at the beginning of the file.
    Question 3
    CBSEENCO12011641

    Evaluate the following postfix notation of expression. Show status of the stack after every operation.
    22,11,/,14,10,,+,5,2

    Solution
    Element Stack
    22 22
    11 22, 11
    / 2
    14 2,14
    10 2,14,10
    - 2,4
    + 6
    5 6,5
    - 1    
    Question 4
    CBSEENCO12011642

    Write a statement in Python to perform the following operations:

    • To open a text file “BOOK.TXT” in read mode
    • To open a text file “BOOK.TXT” in write mode

    Solution
    f1 = open('BOOK.TXT','r')
    f2 = open('BOOK.TXT','w')

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