Reverse a list in-place

Q: Reverse a list in-place

This question evaluates a candidate's ability to implement an in-place list reversal and the underlying competencies in array/list manipulation, index/pointer management, and analysis of space and time complexity.

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Question

Coding Task: Reverse a List In-Place (Python)

Context

You're implementing a utility function during a technical screen. The function must reverse a Python list in-place without allocating another list.

Requirements

Implement a function that reverses a Python list in-place.
Constraints:
1. No slicing (e.g., arr[::-1]), no list(), and no reversed().
2. Time complexity: O(n).
3. Extra space: O(1).
4. Must work for empty lists, and for odd/even-length lists.
Deliverables:
1. The function implementation.
2. Brief correctness reasoning.
3. Time and space complexity.
4. Tests that demonstrate in-place behavior (e.g., object id unchanged) and cover edge cases like [], [1], and [1, 4, 8, 12, 16, 20] → [20, 16, 12, 8, 4, 1].

Reverse a list in-place

Coding Task: Reverse a List In-Place (Python)

Context

Requirements

Solution

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Reverse a list in-place

Overview

Coding Task: Reverse a List In-Place (Python)

Context

Requirements

Solution

Comments (0)