GATE DA 2024 Set 1 — Question 41

MCQ+2 / -0.67EasyRecursionFunctions, File & Error HandlingProgramming, Data Structures & AlgorithmsListsData Types & Control Statements

Programming, Data Structures & Algorithms → Data Types & Control Statements → Lists

Last updated 5 September 2026

Question

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.

Correct answer (C) It reverses the list D between indices s1 and s2, both inclusive. Solution The function fun(D, s1, s2) works as follows: 1. It checks if the start index s1 is less than the end index s2 . 2. If true, it swaps the elements at D[s1] and D[s2] . 3. It then recursively calls itself with s1 incremented by 1 and s2 decremented by 1 (fun(D, s1+1, s2-1)). This process continues swapping the first and last elements of the current range, then the second and second-to-last, and so on, moving inwards until s1 >= s2 . This effectively reverses the portion of the list D from index s1 to s2 . Turn this into a strength. Explore AI-powered practice and doubt support with Success Tracker.

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Correct answer (C) It reverses the list D between indices s1 and s2, both inclusive. Solution The function fun(D, s1, s2) works as follows: 1. It checks if the start index s1 is less than the end index s2 . 2. If true, it swaps the elements at D[s1] and D[s2] . 3. It then recursively calls itself with s1 incremented by 1 and s2 decremented by 1 (fun(D, s1+1, s2-1)). This process continues swapping the first and last elements of the current range, then the second and second-to-last, and so on, moving inwards until s1 >= s2 . This effectively reverses the portion of the list D from index s1 to s2 .

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