Rotation Check Using strstr | Dataford Interview Questions

Your question is Rotation Check Using strstr. Start with the requirements on the right.

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Problem

In Pocket Gems' Episode, a compact string may represent an ordered sequence of story-state tokens. Given two strings s1 and s2, determine whether s2 is a rotation of s1, meaning it can be produced by moving some prefix of s1 to its end without changing the character order.

Your solution must use at most one substring-search operation, equivalent to one call to C's strstr. Do not search for every possible rotation individually.

Formal Specification

Implement is_rotation(s1, s2).

Input: Two strings s1 and s2 containing arbitrary characters.
Output: Return True if s2 is a rotation of s1; otherwise, return False.
Two empty strings are considered rotations of each other.

Constraints

0 <= len(s1), len(s2) <= 10^5
Strings may contain arbitrary characters.
The substring search may be performed at most once.
A rotation preserves the original string length.

Function Signature

def is_rotation(s1, s2):