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01. Create a list of integers from 1 to nE02. Access elements by positive and negative indexE03. Slice a list to get first and last three itemsE04. Append an item and extend a listE05. Insert and remove elements in a listE06. Find element index or return -1E07. Count occurrences of a value in a listE08. Reverse a list in-place and by slicingE09. Sort a list of numbers ascending and descendingE10. Convert between lists and tuplesE11. Interleave two lists element by elementM12. Flatten a single-level list of listsM13. Filter a list using a predicateM14. Map a function over a listM15. Rotate a list by k positionsM16. Get unique elements preserving orderM17. Partition a list by a conditionM18. Replace a sublist slice with another listM19. Group equal consecutive values into sublistsH20. Reconstruct a list from value-count tuplesH

Problem No 18

Replace a sublist slice with another list

Medium

≈ 20 minute session

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Summary

Replace a slice of a list with the contents of another list, following Python slice semantics.

Problem statement

Create replace_slice(lst, start, end, replacement) that returns a new list where the slice lst[start:end] (using Python's slicing rules: start inclusive, end exclusive; start or end may be None or negative) is replaced by the elements from replacement (a list). Do not modify the original list. The function should follow Python's semantics for slices, including inserting when the slice is empty.

Task

Understand Python slice semantics and learn how to replace parts of a list safely, returning a new list.

Examples

Replace a middle slice

Input

replace_slice([1,2,3,4,5], 1, 3, [9,9])

Output

[1, 9, 9, 4, 5]

Explanation

Elements at indices 1 and 2 are replaced by [9,9].

Input format

Four arguments: a list, start index (or None), end index (or None), and a replacement list.

Output format

A new list with the specified slice replaced by the replacement contents.

Constraints

Follow Python's list slicing semantics exactly. Do not modify the input list.

Samples

Sample input 0

replace_slice([1,2,3], None, None, [9])

Sample output 0

[9]

Explanation 0

Replacing the whole list with [9].

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