List Processing and In-Place Mutation Previous Year Questions (PYQs) for GATE DA: 2+ Solved Questions with Step-by-Step Solutions

    Solve 2+ List Processing and In-Place Mutation previous year questions for GATE DA with answers and detailed solutions. Free sample questions below.

    Chapter Roadmap: List Processing and In-Place Mutation

    Chapter Roadmap

    Chapter journey

    1. Recursive List Processing and In-Place Mutation
      Current topic. High-importance tracing.
      • Single-index recursive scans
      • Adjacent-swap counting
      • Two-pointer reversal
    2. Chapter mastery
      • Track exact list state after every swap
      • Decide if call is scan or reversal
      • Predict final return value and list
    Weight hint: Core tracing topic. Small code pieces can carry good marks through careful step-by-step execution.

    Topic Hero: Recursion Meets Mutable Lists

    Topic Hero: Recursion Meets Mutable Lists

    A Python list is mutable. If a recursive function changes the list, the changed list is visible to all deeper recursive calls.

    Two core shapes appear repeatedly:

    Shape Indices used Typical operation
    Single-index scan i Compare and possibly swap L[i] and L[i+1]
    Two-pointer reversal s1, s2 Swap D[s1] and D[s2], then move inward
    Key idea: The list is shared, but the index variables are local to each recursive call.

    List Processing and In-Place Mutation: Solved Questions with Step-by-Step Explanations (2 Problems)

    Question 1 · Programming, Data Structures and Algorithms NAT
    Consider the given Python program.

    def fun(L, i=0):
        if i >= len(L)-1:
            return 0
        if L[i] > L[i+1]:
            L[i+1], L[i] = L[i], L[i+1]
            return 1+fun(L, i+1)
        else:
            return fun(L, i+1)

    data = [5, 3, 4, 1, 2]
    count = 0
    for _ in range(len(data)):
        count += fun(data)
    print(count)

    The output of the program is __________ . (Answer in integer)
    Question 2 · Programming, Data Structures and Algorithms MCQ
    Consider the following Python function:
    def fun(D, s1, s2):
    if s1 < s2:
    D[s1], D[s2] = D[s2], D[s1]
    fun(D, s1+1, s2-1)
    What does this Python function fun() do? Select the ONE appropriate option
    below.
    1. A.

      It finds the smallest element in D from index s1 to s2, both inclusive.

    2. B.

      It performs a merge sort in-place on this list D between indices s1 and s2, both inclusive.

    3. C.

      It reverses the list D between indices s1 and s2, both inclusive.

    4. D.

      It swaps the elements in D at indices s1 and s2, and leaves the remaining elements unchanged.

    More previous year questions (pyqs) in this unit

    chapter
    List Processing and In-Place Mutation Previous Year Questions (PYQs) for GATE DA: 2+ Solved Questions with Step-by-Step Solutions

    Solve 2+ List Processing and In-Place Mutation previous year questions for GATE DA with answers and detailed solutions. Free sample questions below.

    A question from this chapter

    Question 1
    Consider the given Python program.

    def fun(L, i=0):
        if i >= len(L)-1:
            return 0
        if L[i] > L[i+1]:
            L[i+1], L[i] = L[i], L[i+1]
            return 1+fun(L, i+1)
        else:
            return fun(L, i+1)

    data = [5, 3, 4, 1, 2]
    count = 0
    for _ in range(len(data)):
        count += fun(data)
    print(count)

    The output of the program is __________ . (Answer in integer)
    Question 2
    Consider the following Python function:
    def fun(D, s1, s2):
    if s1 < s2:
    D[s1], D[s2] = D[s2], D[s1]
    fun(D, s1+1, s2-1)
    What does this Python function fun() do? Select the ONE appropriate option
    below.
    Free preview ends here

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